PATENT DOCUMENT

Publication Number: US-11985463-B2
Application Number: US-202318197672-A
Country: US
Kind Code: B2

Title: Headphones with increased back volume

Abstract:
This disclosure includes several different features suitable for use in circumaural and supra-aural headphones designs. Designs that include earpad assemblies that improve acoustic isolation are discussed. User convenience features that include automatically detecting the orientation of the headphones on a user&#39;s head are also discussed. Various power-saving features, design features, sensor configurations and user comfort features are also discussed.

Claims:
What is claimed is: 
     
       1. An earpiece suitable for use with headphones, the earpiece comprising:
 an earpiece housing defining an interior volume having a central region surrounded by an annular region, the earpiece housing including a cover plate disposed over the central region and having a plurality of apertures formed there through; 
 an array of capacitive sensors disposed within the interior volume and coupled to the cover plate; 
 an annular earpad coupled to the earpiece housing and surrounding the plurality of apertures formed through the cover plate; and 
 an acoustic driver disposed within the interior volume and aligned to emit sound through the plurality of apertures formed in the cover plate. 
 
     
     
       2. The earpiece set forth in  claim 1  wherein the array of capacitive sensors extends across the plurality of apertures. 
     
     
       3. The earpiece set forth in  claim 2  wherein the array of capacitive sensors has a plurality of openings formed there through, each opening in the plurality of openings being aligned with one of the apertures in the plurality of apertures. 
     
     
       4. The earpiece set forth in  claim 1  wherein the array of capacitive sensors is configured to detect a pattern formed by one or more physical features. 
     
     
       5. The earpiece set forth in  claim 1  wherein the array of capacitive sensors is configured to, when the earpiece is worn over a human ear, detect whether the earpiece is worn over a left ear or a right ear. 
     
     
       6. The earpiece set forth in  claim 1  wherein the array of capacitive sensors is configured to, when the earpiece is worn over a human ear, detect contours of the ear. 
     
     
       7. The earpiece set forth in  claim 1 , wherein the array of capacitive sensors defines multiple openings that allow audio waves generated by an acoustic driver to exit the earpiece housing through the multiple openings. 
     
     
       8. The earpiece set forth in  claim 1  further comprising a frame disposed within the interior volume and coupling the acoustic driver to the earpiece housing. 
     
     
       9. The earpiece set forth in  claim 1  further comprising one or more proximity sensors arranged to, when the earpiece is worn by a user, emit infrared light towards an ear of the user. 
     
     
       10. An earpiece suitable for use with headphones, the earpiece comprising:
 an earpiece housing defining an interior volume having a central region surrounded by an annular region, the earpiece housing including a cover plate disposed over the central region and having a plurality of apertures formed there through; 
 an array of capacitive sensors coupled to the cover plate and arranged in a grid pattern that extends across the plurality of apertures, the array of capacitive sensors having a plurality of openings formed there through, each opening in the plurality of openings being aligned with one of the apertures in the plurality of apertures; 
 an annular earpad coupled to the earpiece housing and surrounding the plurality of apertures formed through the cover plate; and 
 an acoustic driver disposed within the interior volume and aligned to emit sound through the plurality of apertures formed in the cover plate and through the openings of the array of capacitive sensors. 
 
     
     
       11. The earpiece set forth in  claim 10  wherein the array of capacitive sensors is configured to, when the earpiece is worn over a human ear, detect whether the earpiece is worn over a left ear or a right ear. 
     
     
       12. The earpiece set forth in  claim 10  wherein the array of capacitive sensors is configured to, when the earpiece is worn over a human ear, detect contours of the ear. 
     
     
       13. Headphones comprising:
 a headband having first and second opposing ends; 
 a first earpiece coupled to the first end of the headband; and 
 a second earpiece coupled to the second end of the headband; 
 wherein each of the first and second earpieces comprises:
 an earpiece housing defining an interior volume having a central region surrounded by an annular region, the earpiece housing including a cover plate disposed over the central region and having a plurality of apertures formed there through; 
 an array of capacitive sensors disposed within the interior volume and coupled to the cover plate; 
 an annular earpad coupled to the earpiece housing and surrounding the plurality of apertures formed through the cover plate; and 
 an acoustic driver disposed within the interior volume and aligned to emit sound through the plurality of apertures formed in the cover plate. 
 
 
     
     
       14. The headphones set forth in  claim 13  wherein, in each of the first and second earpieces, the array of capacitive sensors extends across the plurality of apertures. 
     
     
       15. The headphones set forth in  claim 14  wherein, in each of the first and second earpieces, the array of capacitive sensors has a plurality of openings formed there through, each opening in the plurality of openings being aligned with one of the apertures in the plurality of apertures. 
     
     
       16. The headphones set forth in  claim 13  wherein, in each of the first and second earpieces, the array of capacitive sensors is configured to, when the earpiece is worn over a human ear, whether the earpiece is worn over a left ear or a right ear. 
     
     
       17. The headphones set forth in  claim 13  wherein, in each of the first and second earpieces, the array of capacitive sensors is configured to, when the earpiece is worn over a human ear, detect contours of the ear. 
     
     
       18. The headphones set forth in  claim 13  wherein, in each of the first and second earpieces, the array of capacitive sensors defines multiple openings that allow audio waves generated by an acoustic driver to exit the earpiece housing through the multiple openings. 
     
     
       19. The headphones set forth in  claim 13  further comprising one or more proximity sensors arranged to, when the earpiece is worn by a user, emit infrared light towards an ear of the user. 
     
     
       20. The headphones set forth in  claim 13  wherein, in each of the first and second earpieces, the array of capacitive sensors is arranged in a grid pattern that extends across the plurality of apertures.

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 17/804,274 filed May 26, 2022, which is a continuation of U.S. application Ser. No. 16/878,565 filed May 19, 2020, now U.S. Pat. No. 11,375,306, entitled “HEADPHONES WITH INCREASED BACK VOLUME,” which is a continuation of International Application No. PCT/US2018/062143 filed Nov. 20, 2018, which claims priority to U.S. Provisional Application No. 62/588,801 filed Nov. 20, 2017. The disclosure of each of the Ser. No. 16/878,565, PCT/US2018/062143 and 62/588,801 applications are herein incorporated by reference in their entirety for all purposes. 
    
    
     FIELD 
     The described embodiments relate generally to various headphone features. More particularly, the various features help improve the overall user experience by incorporating an array of sensors and new mechanical features into the headphones. 
     BACKGROUND 
     Headphones have now been in use for over 100 years, but the design of the mechanical frames used to hold the earpieces against the ears of a user have remained somewhat static. For this reason, some over-head headphones are difficult to easily transport without the use of a bulky case or by wearing them conspicuously about the neck when not in use. Conventional interconnects between the earpieces and band often use a yoke that surrounds the periphery of each earpiece, which adds to the overall bulk of each earpiece. Furthermore, headphones users are required to manually verify that the correct earpieces are aligned with the ears of a user any time the user wishes to use the headphones. Consequently, improvements to the aforementioned deficiencies are desirable. 
     SUMMARY 
     This disclosure describes several improvements on circumaural and supra-aural headphone frame designs. 
     A portable listening device is disclosed and includes the following: first and second earpieces; an adjustable length headband assembly coupling the first earpiece to the second earpiece, the adjustable length headband assembly comprising: a housing component defining an interior volume; and a hollow stem coupling the first earpiece to the housing component and being configured to telescope into and out of the interior volume; and a data synchronization cable extending through the hollow stem and the interior volume to electrically couple the first and second earpieces, a coiled portion of the data synchronization cable being disposed within the hollow stem. 
     Headphones are disclosed and include the following: first and second earpieces; an adjustable length headband assembly coupling the first earpiece to the second earpiece, the adjustable length headband assembly comprising: a housing component defining an interior volume; a hollow stem coupling the first earpiece to the housing component and being configured to telescope into and out of the interior volume; a first stabilizing element disposed at a distal end of the hollow stem; a second stabilizing element disposed at a distal end of the housing component; and a data synchronization cable extending through both the hollow stem and the interior volume to electrically couple the first and second earpieces. 
     A portable listening device is disclosed and includes the following: an earpiece, comprising: an earpiece housing; and a latching mechanism disposed within the earpiece housing, the latching mechanism having a latch plate defining an aperture and a switch configured to shift a position of the latch plate from a first position to a second position; and a headband assembly coupled to the earpiece by the latching mechanism, the headband assembly comprising a stem base positioned at a first end of the headband assembly, the stem base extending through the aperture. 
     An earpiece is disclosed and includes the following: an earpiece housing defining a stem opening; a speaker disposed within the earpiece housing; and a latching mechanism disposed within the earpiece housing, the latching mechanism having a latch plate defining an asymmetric aperture and a switch configured to shift a position of the latch plate from a first position in which a first portion of the asymmetric aperture is aligned with the stem opening to a second position in which a second portion of the asymmetric aperture is aligned with the stem opening, wherein the first portion of the asymmetric aperture is smaller than the second portion. 
     Other aspects and advantages of the invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the described embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure will be readily understood by the following detailed description in conjunction with the accompanying drawings, wherein like reference numerals designate like structural elements, and in which: 
         FIG.  1 A  shows a front view of an exemplary set of over ear or on-ear headphones; 
         FIG.  1 B  shows headphone stems extending different distances from a headband assembly; 
         FIG.  2 A  shows a perspective view of a first side of headphones with synchronized headphone stems; 
         FIGS.  2 B- 2 C  show cross-sectional views of the headphones depicted in  FIG.  2 A  in accordance with section lines A-A and B-B, respectively; 
         FIG.  2 D  shows a perspective view of an opposite side of the headphones depicted in  FIG.  2 A ; 
         FIG.  2 E  shows a cross-sectional view of the headphones depicted in  FIG.  2 D  in accordance with section line C-C; 
         FIGS.  2 F- 2 G  show perspective views of a second side of headphones with synchronized headphone stems and a unitary spring band; 
         FIGS.  2 H- 2 I  show cross-sectional views of the headphones depicted in  FIGS.  2 F- 2 G  in accordance with section lines D-D and E-E, respectively; 
         FIG.  3 A  shows exemplary headphones having a headband assembly configured to synchronize adjustment of the positions of its earpieces; 
         FIG.  3 B  shows a cross-sectional view of a headband assembly when the headphones are expanded to their largest size; 
         FIG.  3 C  shows a cross-sectional view of the headband assembly when the headphones are contracted to a smaller size; 
         FIGS.  3 D- 3 F  show perspective top and cross-sectional views of a headband assembly configured to synchronize earpiece position; 
         FIGS.  3 G- 3 H  show a top view of an earpiece synchronization assembly; 
         FIGS.  3 I- 3 J  show a flattened schematic view of another earpiece synchronization system similar to the one depicted in  FIGS.  3 G- 3 H ; 
         FIGS.  3 K- 3 L  show cutaway views of headphones  360  that are suitable for incorporation of either one of the earpiece synchronization systems depicted in  FIGS.  3 G- 3 J ; 
         FIGS.  3 M- 3 N  show perspective views of the earpiece synchronization system depicted in  FIGS.  3 G- 3 H  in retracted and extended positions as well as a data synchronization cable; 
         FIG.  3 O  shows a portion of a canopy structure and how an earpiece synchronization system can be routed through reinforcement members of the canopy structure; 
         FIGS.  3 P- 3 Q  show gearing located at opposing ends of a headband assembly for another alternative earpiece synchronization system; 
         FIGS.  4 A- 4 B  show front views of headphones having off-center pivoting earpieces; 
         FIG.  5 A  shows an exemplary pivot mechanism that includes torsion springs; 
         FIG.  5 B  shows the pivot mechanism depicted in  FIG.  5 A  positioned behind a cushion of an earpiece; 
         FIG.  6 A  shows a perspective view of another pivot mechanism that includes leaf springs; 
         FIG.  6 B- 6 D  show a range of motion of an earpiece using the pivot mechanism depicted in  FIG.  6 A ; 
         FIG.  6 E  shows an exploded view of the pivot mechanism depicted in  FIG.  6 A ; 
         FIG.  6 F  shows a perspective view of another pivot mechanism; 
         FIG.  6 G  shows yet another pivot mechanism; 
         FIGS.  6 H- 6 I  show the pivot mechanism depicted in  FIG.  6 G  with one side removed in order to illustrate rotation of a stem base in different positions; 
         FIG.  6 J  shows a cutaway perspective view of the pivot assembly of  FIG.  6 G  disposed within an earpiece housing; 
         FIGS.  6 K- 6 L  show partial cross-sectional side views of the pivot assembly positioned within the earpiece housing with helical springs in relaxed and compressed states; 
         FIGS.  6 M- 6 N  show side views of two different rotational positions of stem base isolated from its pivot assembly; 
         FIG.  7 A  shows multiple positions of a spring band suitable for use in a headband assembly; 
         FIG.  7 B  shows a graph illustrating how spring force varies based on spring rate as a function of displacement of the spring band depicted in  FIG.  7 A ; 
         FIGS.  8 A- 8 B  show a solution for preventing discomfort caused by headphones wrapping too tightly around the neck of a user; 
         FIGS.  8 C- 8 D  show how separate and distinct knuckles can be arranged along the lower side of a spring band to prevent the spring band from returning to a neutral position; 
         FIGS.  8 E- 8 F  show how springs joining a headband assembly to earpieces can cooperate with a spring band to set the actual amount of force applied to a user by headphones; 
         FIGS.  8 G- 8 H  show another way in which to limit the range of motion of a pair of headphones using a low spring-rate band; 
         FIG.  9 A  shows an earpiece of headphones positioned over an ear of a user; 
         FIG.  9 B  shows positions of capacitive sensors beneath a surface and proximate ear contours associated with the ear; 
         FIG.  10 A  shows a top view of an exemplary head of a user wearing headphones; 
         FIG.  10 B  shows a front view of the headphones depicted in  FIG.  10 A ; 
         FIGS.  10 C- 10 D  show top views of the headphones depicted in  FIG.  10 A  and how earpieces of the headphones are able to rotate about respective yaw axes; 
         FIGS.  10 E- 10 F  show flow charts describing control methods that can be carried out when roll and/or yaw of the earpieces with respect to the headband is detected; 
         FIG.  10 G  shows a system level block diagram of a computing device  1070  that can be used to implement the various components described herein; 
         FIGS.  11 A- 11 C  show foldable headphones; 
         FIGS.  11 D- 11 F  show how earpieces of foldable headphones can be folded towards an exterior-facing surface of a deformable band region; 
         FIGS.  12 A- 12 B  show a headphones embodiment that can be transitioned from an arched state to a flattened state by pulling on opposing sides of a spring band; 
         FIGS.  12 C- 12 D  show side views of a foldable stem region in arched and flattened states, respectively; 
         FIG.  12 E  shows a side view of one end of the headphones depicted in  FIG.  12 D ; 
         FIGS.  13 A- 13 B  show partial cross-sectional views of headphones using an off-axis cable to transition between an arched state and a flattened states; 
         FIGS.  14 A- 14 C  show partial cross-sectional views of headphones having a foldable stem region constrained at least in part by an elongating pin that delays flattening of the headphones through a first portion of the travel of the earpieces of the headphones; 
         FIGS.  15 A- 15 F  show various views of headband assembly  1500  from different angles and in different states; 
         FIGS.  16 A- 16 B  show a headband assembly in folded and arched states; 
         FIGS.  17 - 18    show views of another foldable headphones embodiment; 
         FIG.  19    shows one side of a headband housing as well as a telescoping member extending from the end of a headband housing; 
         FIG.  20 A  shows an exploded view of the side of the headband housing depicted in  FIG.  20 A ; 
         FIG.  20 B  shows a cross-sectional view of a first end of a lower housing component in accordance with section line F-F depicted in  FIG.  20 A ; 
         FIG.  20 C  shows a cross-sectional view of a second end of the lower housing component in accordance with section line G-G depicted in  FIG.  20 A ; 
         FIG.  20 D  shows a perspective view of a bushing, which defines multiple finger channels spaced radially around an interior-facing surface of the bushing; 
         FIG.  21 A  shows a perspective view of a spring member and one end of a telescoping member; 
         FIG.  21 B  shows spring fingers of the spring member engaged within a first set of opening defined by the end of the telescoping member; 
         FIG.  21 C  shows the spring member shifted so that the spring fingers are engaged within a second set of openings defined by the end of the telescoping member; 
         FIGS.  21 D- 21 G  show various locking mechanisms positioned at an opening defined by a lower housing assembly through which a telescoping assembly extends; 
         FIGS.  22 A- 22 E  depict various extended and contracted coil configurations for a portion of a synchronization cable disposed within a lower housing component; 
         FIG.  23 A  shows an exploded view of components associated with a data plug; 
         FIG.  23 B  shows a telescoping member fully assembly with threaded fastener fully engaged within a threaded opening in order to keep a data plug securely positioned; 
         FIG.  23 C  shows a cross-sectional view of telescoping member in accordance with section line H-H of  FIG.  23 B ; 
         FIG.  23 D  shows a perspective view of a portion of a data plug; 
         FIG.  23 E  shows a cross-sectional side view of the portion of the data plug and depicts multiple glue channels positioned on opposing sides of the body of the data plug; 
         FIG.  23 F  shows a data plug glued to a stem base, which is in turn positioned within a recess defined by an earpiece; 
         FIG.  23 G  shows a cross-sectional view of the data plug disposed within a recess defined by the stem base, which is in turn positioned within a recess of an earpiece; 
         FIG.  24 A  shows perspective views of an earpiece and an earpad; 
         FIG.  24 B  shows how earpieces of a pair of headphones can have thin earpads without sacrificing user comfort; 
         FIG.  24 C  shows how posts couple a flexible substrate supporting the earpad to earpiece yokes; 
         FIG.  24 D  shows an earpiece and an axis of rotation about which an earpad is configured to bend to accommodate cranial contours of a user&#39;s head; 
         FIG.  24 E- 24 G  depict another earpiece in a configuration designed to account for cranial contours of a user&#39;s head; 
         FIGS.  25 A- 25 C  show various views of another earpad configuration formed from multiple layers of material; 
         FIG.  25 D  shows how heat-treated regions of a textile layer are in direct contact with the side of a user&#39;s head when the headphones are in active use; 
         FIGS.  26 A- 26 B  show perspective views of an earpad in different orientations; 
         FIG.  26 C- 26 G  show various manufacturing operations for forming an earpad from a block of foam; 
         FIG.  27 A  shows a cross-sectional side view of an exemplary acoustic configuration within an earpiece that could be applied with many of the previously described earpieces; 
         FIG.  27 B  shows an exterior of the earpiece with an input panel removed to illustrate the shape and size of an interior volume associated with a speaker assembly; 
         FIG.  27 C  shows a microphone mounted within an earpiece; 
         FIG.  28    shows an earpiece having an input panel, which can form an exterior facing surface of earpiece; 
         FIGS.  29 A- 29 B  show perspective and cross-sectional views of an outline of an earpiece illustrating a position of distributed battery assemblies within the earpiece; 
         FIG.  29 C  shows how more than two discrete battery assemblies can be incorporated into a single earpiece housing; 
         FIG.  30 A  shows exemplary headphones, which include earpieces joined together by a headband; 
         FIG.  30 B  shows an exemplary carrying/storage case well suited for use with circumaural and supra-aural headphones designs discussed herein; and 
         FIG.  30 C  shows headphones  3000  positioned within a recess of the case; and 
         FIG.  30 D  shows a cross-sectional view of an earpiece in accordance with section line K-K of  FIG.  30 C ; 
         FIG.  30 E  shows a carrying case with headphones positioned therein; 
         FIGS.  31 A- 31 B  show an illuminated button assembly suitable for use with the described headphones; 
         FIGS.  31 C- 31 D  show side views of the illuminated button assembly depicted in  FIGS.  31 A- 31 B  in unactuated and actuated positions, respectively, within a device housing; 
         FIG.  31 E  shows a perspective view of an illuminated window; 
         FIGS.  32 A- 32 B  show perspective views of a pivot assembly associated with a removable earpiece engaged by a stem base of a headphone band; 
         FIGS.  33 A- 33 C  show different views of a latching mechanism of a pivot assembly; 
         FIG.  34 A  shows headphones, which includes earpieces mechanically coupled together by a headband assembly; 
         FIG.  34 B  shows a close up view of a stem region of a headband assembly; 
         FIG.  34 C  shows a close up view of a distal end of a telescoping component; 
         FIG.  34 D  shows a cross-sectional view of a distal end of a telescoping component in accordance with section line L-L as depicted in  FIG.  34 B ; 
         FIG.  34 E  shows a cross-sectional view of a distal end of a lower housing component in accordance with section line M-M as depicted in  FIG.  34 B ; 
         FIGS.  34 F- 34 H  show a number of alternative embodiments that allow for a larger or smaller amount of play to be established between a lower housing component and a telescoping component; and 
         FIGS.  34 I- 34 J  show configurations including a telescoping component disposed within an interior volume defined by a lower housing component. 
     
    
    
     DETAILED DESCRIPTION 
     Representative applications of methods and apparatus according to the present application are described in this section. These examples are being provided solely to add context and aid in the understanding of the described embodiments. It will thus be apparent to one skilled in the art that the described embodiments may be practiced without some or all of these specific details. In other instances, well known process steps have not been described in detail in order to avoid unnecessarily obscuring the described embodiments. Other applications are possible, such that the following examples should not be taken as limiting. 
     In the following detailed description, references are made to the accompanying drawings, which form a part of the description and in which are shown, by way of illustration, specific embodiments in accordance with the described embodiments. Although these embodiments are described in sufficient detail to enable one skilled in the art to practice the described embodiments, it is understood that these examples are not limiting; such that other embodiments may be used, and changes may be made without departing from the spirit and scope of the described embodiments. 
     Headphones have been in production for many years, but numerous design problems remain. For example, the functionality of headbands associated with headphones has generally been limited to a mechanical connection functioning only to maintain the earpieces of the headphones over the ears of a user and provide an electrical connection between the earpieces. Furthermore, the incorporation of headphones into other types of portable listening devices, such as augmented reality and virtual reality headsets has also been slow due to an unwillingness to adapt headphones to new and improved form factors. The headband tends to add substantially to the bulk of the headphones, thereby making storage of the headphones problematic. Stems connecting the headband to the earpieces that are designed to accommodate adjustment of an orientation of the earpieces with respect to a user&#39;s ears also add bulk to the headphones. Stems connecting the headband to the earpieces that accommodate elongation of the headband generally allow a central portion of the headband to shift to one side of a user&#39;s head. This shifted configuration can look somewhat odd and depending on the design of the headphones can also make the headphones less comfortable to wear. 
     While some improvements such as wireless delivery of media content to the headphones has alleviated the problem of cord tangle, this type of technology introduces its own batch of problems. For example, because wireless headphones require battery power to operate, a user who leaves the wireless headphones turned on could inadvertently exhaust the battery of the wireless headphones, making them unusable until a new battery can be installed or for the device to be recharged. Another design problem with many headphones is that a user must generally figure out which earpiece corresponds to which ear to prevent the situation in which the left audio channel is presented to the right ear and the right audio channel is presented to the left ear. 
     A solution to the unsynchronized positioning of the earpieces is to incorporate an earpiece synchronization component taking the form of a mechanical mechanism disposed within the headband that synchronizes the distance between the earpieces and respective ends of the headband. This type of synchronization can be performed in multiple ways. In some embodiments, the earpiece synchronization component can be a cable extending between both stems that can be configured to synchronize the movement of the earpieces. The cable can be arranged in a loop where different sides of the loop are attached to respective stems of the earpieces so that motion of one earpiece away from the headband causes the other earpiece to move the same distance away from the opposite end of the headband. Similarly, pushing one earpiece towards one side of the headband translates the other earpiece the same distance towards the opposite side of the headband. In some embodiments, the earpiece synchronization component can be a rotating gear embedded within the headband can be configured to engage teeth of each stem to keep the earpieces synchronized. 
     One solution to the conventional bulky connections between headphones stems and earpieces is to use a spring-driven pivot mechanism to control motion of the earpieces with respect to the band. The spring-driven pivot mechanism can be positioned near the top of the earpiece, allowing it to be incorporated within the earpiece instead of being external to the earpiece. In this way, pivoting functionality can be built into the earpieces without adding to the overall bulk of the headphones. Different types of springs can be utilized to control the motion of the earpieces with respect to the headband. Specific examples that include torsional springs and leaf springs are described in detail below. The springs associated with each earpiece can cooperate with springs within the headband to set an amount of force exerted on a user wearing the headphones. In some embodiments, the springs within the headband can be low spring-rate springs configured to minimize the force variation exerted across a large spectrum of users with different head sizes. In some embodiments, the travel of the low-rate springs in the headband can be limited to prevent the headband from clamping to tightly about the neck of a user when being worn around the neck. 
     One solution to the large headband form-factor problem is to design the headband to flatten against the earpieces. The flattening headband allows for the arched geometry of the headband to be compacted into a flat geometry, allowing the headphones to achieve a size and shape suitable for more convenient storage and transportation. The earpieces can be attached to the headband by a foldable stem region that allows the earpieces to be folded towards the center of the headband. A force applied to fold each earpiece in towards the headband is transmitted to a mechanism that pulls the corresponding end of the headband to flatten the headband. In some embodiments, the stem can include an over-center locking mechanism that prevents inadvertent return of the headphones to an arched state without requiring the addition of a release button to transition the headphones back to the arched state. 
     A solution to the power management problems associated with wireless headphones includes incorporating an orientation sensor into the earpieces that can be configured to monitor an orientation of the earpieces with respect to the band. The orientation of the earpieces with respect to the band can be used to determine whether or not the headphones are being worn over the ears of a user. This information can then be used to put the headphones into a standby mode or shut the headphones down entirely when the headphones are not determined to be positioned over the ears of a user. In some embodiments, the earpiece orientation sensors can also be utilized to determine which ears of a user the earpieces are currently covering. Circuitry within the headphones can be configured to switch the audio channels routed to each earpiece in order to match the determination regarding which earpiece is on which ear of the user. 
     These and other embodiments are discussed below with reference to  FIGS.  1 - 31 E ; however, those skilled in the art will readily appreciate that the detailed description given herein with respect to these figures is for explanatory purposes only and should not be construed as limiting. 
     Symmetric Telescoping Earpieces 
       FIG.  1 A  shows a front view of an exemplary set of over ear or on-ear headphones  100 . Headphones  100  includes a band  102  that interacts with stems  104  and  106  to allow for adjustability of the size of headphones  100 . In particular, stems  104  and  106  are configured to shift independently with respect to band  102  in order to accommodate multiple different head sizes. In this way, the position of earpieces  108  and  110  can be adjusted to position earpieces  108  and  110  directly over the ears of a user. Unfortunately, as can be seen in  FIG.  1 B , this type of configuration allows stems  104  and  106  to become mismatched with respect to band  102 . The configuration shown in  FIG.  1 B  can be less comfortable for a user and additionally lack cosmetic appeal. To remedy these issues, the user would be forced to manually adjust stems  104  and  106  with respect to band  102  in order to achieve a desirable look and comfortable fit.  FIGS.  1 A- 1 B  also show how stems  104  and  106  extend down to a central portion of earpieces  108  in order to allow earpieces  108  to rotate to accommodate the curvature of a user&#39;s head. As mentioned above the portions of stems  104  and  106  that extend down around earpieces  108  increase the diameters of earpieces  108 . 
       FIG.  2 A  shows a perspective view of headphones  200  with a headband  202  configured to solve the problems depicted in  FIGS.  1 A- 1 B . Headband  202  is depicted without a cosmetic covering to reveal internal features. In particular, headband  202  can include a wire loop  204  configured to synchronize the movement of stems  206  and  208 . Wire guides  210  can be configured to maintain a curvature of wire loop  204  that matches the curvature of leaf springs  212  and  214 . Leaf springs  212  and  214  can be configured to define the shape of headband  202  and to exert a force upon the head of a user. Each of wire guides  210  can include openings through which opposing sides of wire loop  204  and leaf springs  212  and  214  can pass. In some embodiments, the openings for wire loop  204  can be defined by low-friction bearings to prevent noticeable friction from impeding the motion of wire loop  204  through the openings. In this way, wire guides  210  define a path along which wire loop  204  extends between stem housings  216  and  218 . Wire loop  204  is coupled to both stem  206  and stem  208  and functions to maintain a distance  120  between an earpiece  122  and stem housing  116  substantially the same as a distance  124  between earpiece  126  and stem housing  118 . A first side  204 - 1  of wire loop  204  is coupled to stem  206  and a second side  204 - 2  of wire loop  204  is coupled to stem  208 . Because opposite sides of the wire loop are attached to stems  206  and  208  movement of one of the stems results in movement of the other stem in the same direction. 
       FIG.  2 B  shows a cross-sectional view of a portion of stem housing  116  in accordance with section line A-A. In particular,  FIG.  2 B  shows how a protrusion  228  of stem  206  engages part of wire loop  204 . Because protrusion  228  of stem  206  is coupled with wire loop  204 , when a user of headphones  100  pulls earpiece  222  farther away from stem housing  216 , wire loop  204  is also pulled causing wire loop  204  to circulate through headband  202 . The circulation of wire loop  204  through headband  202  adjusts the position of earpieces  226 , which is similarly coupled to wire loop  204  by a protrusion of stem  208 . In addition to forming a mechanical coupling with wire loop  204 , protrusion  228  can also be electrically coupled to wire loop  204 . In some embodiments, protrusion  228  can include an electrically conductive pathway  230  that electrically couples wire loop  204  to electrical components within earpiece  222 . In some embodiments, wire loop  204  can be formed from an electrically conductive material, so that signals can be transferred between components within earpieces  222  and  226  by way of wire loop  204 . 
       FIG.  2 C  shows another cross-sectional view of stem housing  116  in accordance with section line B-B. In particular,  FIG.  2 C  shows how wire loop  204  engages pulley  232  within stem housing  216 . Pulley  232  minimizes any friction generated by the movement of earpiece  222  closer or farther away from stem housing  216 . Alternatively, wire loop  204  can be routed through a static bearing within stem housing  216 . 
       FIG.  2 D  shows another perspective view of headphones  200 . In this view, it can be seen that first side  204 - 1  and second side  204 - 2  of wire loop  204  shift laterally as they cross from one side of headband  202  to the other. This can be accomplished by the openings defined by wire guides  210  being gradually offset so that by the time sides  204 - 1  and  204 - 2  reach stem housing  218 , second side  204 - 2  is centered and aligned with stem  208 , as depicted in  FIG.  2 E . 
       FIG.  2 E  shows how second side  204 - 2  is engaged by protrusion  234 . Because stems  206  and  208  are attached to respective first and second sides of wire loop  204 , pushing earpiece  226  towards stem housing  218  also results in earpiece  222  being pushed towards stem housing  216 . Another advantage of the configuration depicted in  FIGS.  2 A- 2 E  is that regardless of the direction of travel of stems  206  and  208 , wire loop  204  always stays in tension. This keeps the amount of force needed to extend or retract earpieces  222  and  226  consistent regardless of direction. 
       FIGS.  2 F- 2 G  show perspective views of headphones  250 . Headphones  250  are similar to headphones  200  with the exception that only a single leaf spring  252  is used to connect stem housing  254  to stem housing  256 . In this embodiment, wire loop  258  can be positioned to either side of leaf spring  252 . Instead of being positioned directly below one side of wire loop  258 , stems  260  and  262  can be positioned directly between the two sides of wire loop  258  and connected to one side of wire loop  258  by an arm of stems  260  and  262 . 
       FIGS.  2 H and  2 I  show cross-sectional views of an interior portion of stem housings  254  and  256 .  FIG.  2 H  shows a cross-sectional view of stem housing  254  in accordance with section line D-D.  FIG.  2 H  shows how stem  260  can include a laterally protruding arm  268  that engages wire loop  258 . In this way, laterally protruding arm  268  couples stem  260  to wire loop  258  so that when earpiece  264  is moved earpiece  266  is kept in an equivalent position.  FIG.  2 I  shows a cross-sectional view of stem housing  256  in accordance with section line E-E.  FIG.  2 I  also shows how wire loop  258  can be routed within stem housing  256  by pulleys  270  and  272 . By routing wire loop  258  above stem  262  any interference between wire loop  258  and stem  206  can be avoided. 
       FIGS.  3 A- 3 C  show another headphones embodiment configured to solve problems described in  FIGS.  1 A- 1 B .  FIG.  3 A  shows headphones  300 , which includes headband assembly  302 . Headband assembly  302  is joined to earpieces  304  and  306  by stems  308  and  310 . A size and shape of headband assembly  302  can vary depending on how much adjustability is desirable for headphones  300 . 
       FIG.  3 B  shows a cross-sectional view of headband assembly  302  when headphones  300  are expanded to their largest size. In particular,  FIG.  3 B  shows how headband assembly  302  includes a gear  312  configured to engage teeth defined by the ends of each of stems  308  and  310 . In some embodiments, stems  308  and  310  can be prevented from pulling completely out of headband assembly  302  by spring pins  314  and  316  by engaging openings defined by stems  308  and  310 . 
       FIG.  3 C  shows a cross-sectional view of headband assembly  302  when headphones  300  are contracted to a smaller size. In particular,  FIG.  3 C  shows how gear  312  keeps the position of stems  308  and  310  synchronized on account of any movement of stem  308  or stem  310  being translated to the other stem by gear  312 . In some embodiments, a stiffness of the housing defining the exterior of headband assembly  302  can be selected to match the stiffness of stems  308  and  310  to provide a user of headphones  300  with a headband having a more consistent feel. 
       FIG.  3 D  shows an alternative embodiment of stems  308  and  310 . A cover concealing the ends of stems  308  and  310  has been removed to more clearly show the features of the mechanism synchronizing the positions of the stems. Stem  308  defines an opening  318  extending through a portion of stem  308 . One side of opening  318  has teeth configured to engage gear  320 . Similarly, stem  310  defines an opening  322  extending through a portion of stem  310 . One side of opening  322  has teeth configured to engage gear  320 . Because opposing sides of openings  318  and  322  engage gear  320 , any motion of one of stems  308  and  310  causes the other stem to move. In this way, earpieces positioned at the ends of each of stem  308  and stem  310  are synchronized. 
       FIG.  3 E  shows a top view of stems  308  and  310 .  FIG.  3 E  also shows an outline of a cover  324  for concealing the geared openings defined by stems  308  and  310  and controlling the motion of the ends of stems  308  and  310 .  FIG.  3 F  shows a cross-sectional side view of stems  308  and  310  covered by cover  324 . Gear  320  can include bearing  326  for defining the axis of rotation for gear  320 . In some embodiments, the top of bearing  326  can protrude from cover  324 , allowing a user to adjust the earpiece positions by manually rotating bearing  326 . It should be appreciated that a user could also adjust the earpiece positions by simply pushing or pulling on one of stems  308  and  310 . 
       FIG.  3 G  shows a flattened schematic view of another earpiece synchronization system that utilizes a loop  328  within a headband  330  (the rectangular shape is used merely to show the location of headband  330  and should not be construed as for exemplary purposes only) to keep a distance between each of earpieces  304  and  306  and headband  330  synchronized. Stem wires  332  and  334  couple respective earpieces  304  and  306  to loop  328 . Stem wires  332  and  334  can be formed of metal and soldered to opposing sides of loop  328 . Because stem wires  332  and  334  are coupled to opposing sides of loop  328 , movement of earpiece  306  in direction  336  results in stem wire  332  moving in direction  338 . Consequently, moving earpiece  306  into closer proximity with headband  330  also moves stem wire  332 , which results in earpiece  304  being brought into closer proximity with headband  330 . In addition to showing a new location of earpieces  304  and  306  after being moved into closer proximity to headband  330 ,  FIG.  3 H  shows how moving earpiece  304  in direction  340  automatically moves earpiece  306  in direction  342  and farther away from headband  330 . While not depicted it should be appreciated that headband  330  could include various reinforcement members to keep loop  328  and stem wires  332  and  334  in the depicted shapes. 
       FIGS.  3 I- 3 J  show a flattened schematic view of another earpiece synchronization system similar to the one depicted in  FIGS.  3 G- 3 H .  FIG.  3 I  shows how the ends of stems  344  and  346  can be coupled directly to each other without an intervening loop. By extending stems  344  and  346  into a pattern having a similar shape as loop  328  a similar outcome can be achieved without the need for an additional loop structure. Movement of stems  344  and  346  is assisted by reinforcement members  348 ,  350  and  352 , which help to prevent buckling of stems  344  and  346  while the position of earpieces  304  and  306  are being adjusted. Reinforcement members  348 - 352  can define channels through which stems  344  and  346  smoothly pass. These channels can be particularly helpful in locations where stems  344  and  346  curve. While not defining a curved channel, reinforcement member  352  still serves an important purpose of limiting the direction of travel of the ends of stems  344  and  346  to directions  354  and  356 . Movement in direction  356  results in earpieces moving toward headband  330 , as depicted in  FIG.  3 J . Movement in direction  354  results in earpieces  304  and  306  moving farther away from headband  330 . 
       FIGS.  3 K- 3 L  show cutaway views of headphones  360  that are suitable for incorporation of either one of the earpiece synchronization systems depicted in  FIGS.  3 G- 3 J .  FIG.  3 K  shows headphones  360  with earpieces retracted and stem wires  332  and  334  extending out of headband  330  to engage and synchronize a position of stem assembly  362  with a position of stem assembly  364 . Stem  334  is depicted coupled to support structure  366  within stem assembly  364 , which allows extension and retraction of stem  334  to keep stem assembly  362  synchronized with stem assembly  364 . As depicted, stem assembly  362  is disposed within a channel defined by headband  330 , which allows stem assembly  362  to move relative to headband  330 .  FIG.  3 K  also shows how data synchronization cable  368  can extend through headband  330  and wrap around a portion of both stem wire  334  and stem wire  332 . By wrapping around stem wires  332  and  334 , data synchronization cable  368  is able to act as a reinforcement member to prevent buckling of stem wires  332  and  334 . Data synchronization cable  368  is generally configured to exchange signals between earpieces  304  and  306  in order to keep audio precisely synchronized during playback operations of headphones  360 . 
       FIG.  3 L  shows how the coil configuration of data synchronization cable  368  accommodates extension of stem assemblies  362  and  364 . Data synchronization cable  368  can have an exterior surface with a coating that allows stem wires  332  and  334  to slide through a central opening defined by the coils.  FIG.  3 L  also shows how earpieces  304  and  306  maintain the same distance from a central portion of headband  330 . 
       FIGS.  3 M- 3 N  show perspective views of the earpiece synchronization system depicted in  FIGS.  3 G- 3 H  in retracted and extended positions as well as a data synchronization cable  368 .  FIG.  3 M  shows how stem wire  332  includes an attachment feature  370  that at least partially surrounds a portion of loop  328 . In this way, stem wire  332 , stem wire  334  and support structures  366  move along with loop  328 .  FIG.  3 M  also shows a dashed line illustrating how a covering for headband  330  can at least partially conform with loop  328 , stem wire  332  and stem wire  334 . 
       FIG.  3 O  shows a portion of canopy structure  372  and how an earpiece synchronization system can be routed through reinforcement members  374  of canopy structure  372 . Reinforcement members  374  help guide loop  328  and stem wire  332  along a desired path. In some embodiments, canopy structure  372  can include a spring mechanism that helps keep earpieces secured to a user&#39;s ears. 
       FIGS.  3 P- 3 Q  show gearing located at opposing ends of a headband assembly for another alternative earpiece synchronization system. In particular,  FIG.  3 P  shows how stem  262  has a first end coupled to an earpiece (not depicted) and a second end coupled to gear  380 . By pulling on the earpiece a force  382  can be exerted upon stem  262 , which causes gear  380  to rotate due to its engagement of rack gear  384 . Gear  380  is rigidly coupled to beveled gear component  386 . Beveled gear component  386  in turn induces rotation of beveled gear component  388 . Beveled gear component  388  is rigidly coupled to gear  390 . Rotation of gear  390  in turn induces rotation of elongated gear  392 . Gears  380 ,  386 ,  388  and  390  all move together and are guided along a periphery of elongated gear  392  by bearing  394 . Elongated gear  392  is in turn coupled to a flexible rotary shaft that includes a cable  396  routed through an associated headband assembly. Cable  396  can include layers of high-tensile wire wound over each other at opposing pitch angles that are configured to efficiently transmit rotational motion from one end of cable  396  to another. Rotation of the other end of cable  396  in turn moves a stem at the other end of the headband assembly in sync with stem  262 . A diameter of cable  396  can be between about 0.02 inches and 0.25 inches.  FIG.  3 Q  shows a second position of gears  380 ,  386 ,  388  and  390  after having adjusted a position of stem  262 . 
     Off-Center Pivoting Earpieces 
       FIGS.  4 A- 4 B  show front views of headphones  400  having off-center pivoting earpieces.  FIG.  4 A  shows a front view of headphones  400 , which includes headband assembly  402 . In some embodiments, headband assembly  402  can include an adjustable band and stems for customizing the size of headphones  400 . Each end of headband assembly  402  is depicted being coupled to an upper portion of earpieces  404 . This differs from conventional designs, which place the pivot point in the center of earpieces  404  so that earpieces can naturally pivot in a direction that allows earpieces  404  to move to an angle in which earpieces  404  are positioned parallel to a surface of a user&#39;s head. Unfortunately, this type of design generally requires bulky arms that extend to either side of earpiece  404 , thereby substantially increasing the size and weight of earpieces  404 . By locating pivot point  406  near the top of earpieces  404 , associated pivot mechanism components can be packaged within earpieces  404 . 
       FIG.  4 B  shows an exemplary range of motion  408  for each of earpieces  404 . Range of motion  408  can be configured to accommodate a majority of users based on studies performed on average head size measurements. This more compact configuration can still perform the same functions as the more traditional configuration described above, which includes applying a force through the center of the earpiece and establishing an acoustic seal. In some embodiments, range of motion  408  can be about 18 degrees. In some embodiments, range of motion  408  may not have a defined stop but instead grow progressively harder to deform as it gets farther from a neutral position. The pivot mechanism components can include spring elements configured to apply a modest retaining force to the ears of a user when the headphones are in use. The spring elements can also bring earpieces back to a neutral position once headphones  400  are no longer being worn. 
       FIG.  5 A  shows an exemplary pivot mechanism  500  for use in the upper portion of an earpiece. Pivot mechanism  500  can be configured to accommodate motion around two axes, thereby allowing adjustments to both roll and yaw for earpieces  404  with respect to headband assembly  402 . Pivot mechanism  500  includes a stem  502 , which can be coupled to a headband assembly. One end of stem  502  is positioned within bearing  504 , which allows stem  502  to rotate about yaw axis  506 . Bearing  504  also couples stem  502  to torsional springs  508 , which oppose rotation of stem  502  with respect to earpiece  404  about roll axis  510 . Each of torsional springs  508  can also be coupled to mounting blocks  512 . Mounting blocks  512  can be secured to an interior surface of earpiece  404  by fasteners  514 . Bearing  504  can be rotationally coupled to mounting blocks  512  by bushings  516 , which allow bearing  504  to rotate with respect to mounting blocks  512 . In some embodiments, the roll and yaw axes can be substantially orthogonal with respect to one another. In this context, substantially orthogonal means that while the angle between the two axes might not be exactly 90 degrees that an angle between the two axes would stay between 85 and 95 degrees. 
       FIG.  5 A  also depicts magnetic field sensor  518 . Magnetic field sensor  518  can take the form of a magnetometer or Hall Effect sensor capable of detecting motion of a magnet within pivot mechanism  500 . In particular, magnetic field sensor  518  can be configured to detect motion of stem  502  with respect to mounting blocks  512 . In this way, magnetic field sensor  518  can be configured to detect when headphones associated with pivot mechanism  500  are being worn. For example, when magnetic field sensor  518  takes the form of a Hall Effect sensor, rotation of a magnet coupled with bearing  504  can result in the polarity of the magnetic field emitted by that magnet saturating magnetic field sensor  518 . Saturation of the Hall Effect sensor by a magnetic field causes the Hall Effect sensor to send a signal to other electronic devices within headphones  400  by way of flexible circuit  520 . 
       FIG.  5 B  shows a pivot mechanism  500  positioned behind a cushion  522  of earpiece  404 . In this way, pivot mechanism  500  can be integrated within earpiece  404  without impinging on space normally left open to accommodate the ear of a user. Close-up view  524  shows a cross-sectional view of pivot mechanism  500 . In particular, close-up view  524  shows a magnet  526  positioned within a fastener  528 . As stem  502  is rotated about roll axis  510 , magnet  526  rotates with it. Magnetic field sensor  518  can be configured to sense rotation of the field emitted by magnet  526  as it rotates. In some embodiments, the signal generated by magnetic field sensor  518  can be used to activate and/or deactivate headphones  400 . This can be particularly effective when the neutral state of earpiece  404  corresponds to the bottom end of each earpiece  404  is oriented towards the user at an angle that causes earpiece  404  to be rotated away from the users head when worn by most users. By designing headphones  400  in this manner, rotation of magnet  526  away from its neutral position can be used as a trigger that headphones  400  are in use. Correspondingly, movement of magnet  526  back to its neutral position can be used as an indicator that headphones  400  are no longer in use. Power states of headphones  400  can be matched to these indications to save power while headphones  400  are not in use. 
     Close up view  524  of  FIG.  5 B  also shows how stem  502  is able to twist within bearing  504 . Stem  502  is coupled to threaded cap  530 , which allows stem  502  to twist within bearing  504  about yaw axis  506 . In some embodiments, threaded cap  530  can define mechanical stops that limit the range of motion through which stem  502  can twist. A magnet  532  is disposed within stem  502  and is configured to rotate along with stem  502 . A magnetic field sensor  534  can be configured to measure the rotation of a magnetic field emitted by magnet  532 . In some embodiments, a processor receiving sensor readings from magnetic field sensor  534  can be configured to change an operating parameter of headphones  400  in response to the sensor readings indicating a threshold amount of change in the angular orientation of magnet  532  relative to the yaw axis has occurred. 
       FIG.  6 A  shows a perspective view of another pivot mechanism  600  that is configured to fit within a top portion of earpieces  404  of headphones. The overall shape of pivot mechanism  600  is configured to conform with space available within the top portion of the earpieces. Pivot mechanism  600  utilizes leaf springs instead of torsion springs to oppose motion in the directions indicated by arrows  601  of earpieces  404 . Pivot mechanism  600  includes stem  602 , which has one end disposed within bearing  604 . Bearing  604  allows for rotation of stem  602  about yaw axis  605 . Bearing  604  also couples stem  602  to a first end of leaf spring  606  through spring lever  608 . A second end of each of leaf springs  606  is coupled to a corresponding one of spring anchors  610 . Spring anchors  610  are depicted as being transparent so that the position at which the second end of each of leaf springs  606  engages a central portion of spring anchors  610  can be seen. This positioning allows leaf springs  606  to bend in two different directions. Spring anchors  610  couple the second end of each leaf spring  606  to earpiece housing  612 . In this way, leaf springs  606  create a flexible coupling between stem  602  and earpiece housing  612 . Pivot mechanism  600  can also include cabling  614  configured to route electrical signals between two earpieces  404  by way of headband assembly  402  (not depicted). 
       FIGS.  6 B- 6 D  show a range of motion of earpiece  404 .  FIG.  6 B  shows earpiece  404  in a neutral state with leaf springs  606  in an undeflected state.  FIG.  6 C  shows leaf springs  606  being deflected in a first direction and  FIG.  6 D  shows leaf spring  606  being deflected in a second direction opposite the first direction.  FIGS.  6 C- 6 D  also show how the area between cushion  522  and earpiece housing  612  can accommodate the deflection of leaf springs  606 . 
       FIG.  6 E  shows an exploded view of pivot mechanism  600 .  FIG.  6 E  depicts mechanical stops that govern the amount of rotation possible about yaw axis  605 . Stem  602  includes a protrusion  616 , which is configured to travel within a channel defined by an upper yaw bushing  618 . As depicted, the channel defined by upper yaw bushing  618  has a length that allows for greater than 180 degrees of rotation. In some embodiments, the channel can include a detent configured to define a neutral position for earpiece  404 .  FIG.  6 E  also depicts a portion of stem  602  that can accommodate yaw magnet  620 . A magnetic field emitted by magnet  620  can be detected by magnetic field sensor  622 . Magnetic field sensor  622  can be configured to determine an angle of rotation of stem  602  with respect to the rest of pivot mechanism  600 . In some embodiments, magnetic field sensor  622  can be a Hall Effect sensor. 
       FIG.  6 E  also depicts roll magnet  624  and magnetic field sensor  626 , which can be configured to measure an amount of deflection of leaf springs  606 . In some embodiments, pivot mechanism  600  can also include strain gauge  628  configured to measure strain generated within leaf spring  606 . The strain measured in leaf spring  606  can be used to determine which direction and how much leaf spring is being deflected. In this way, a processor receiving sensor readings recorded by strain gauge  628  can determine whether and in which direction leaf springs  606  are bending. In some embodiments, readings received from strain gauge can be configured to change an operating state of headphones associated with pivot mechanism  600 . For example, the operating state can be changed from a playback state in which media is being presented by speakers associated with pivot mechanism  600  to a standby or inactive state in response to the readings from the strain gauge. In some embodiments, when leaf springs  606  are in an undeflected state this can be indicative of headphones associated with pivot mechanism  600  not being worn by a user. In other embodiments, the strain gauge can be positioned upon a headband spring. For this reason, ceasing playback based on this input can be very convenient as it allows a user to maintain a location in a media file until putting the headphones back on the head of the user at which point the headphones can be configured to resume playback of the media file. Seal  630  can close an opening between stem  602  and an exterior surface of an earpiece in order to prevent the ingress of foreign particulates that could interfere with the operation of pivot mechanism  600 . 
       FIG.  6 F  shows a perspective view of another pivot mechanism  650 , which differs in some ways from pivot mechanism  600 . Leaf springs  652  have a different orientation than leaf springs  606  of pivot mechanism  600 . In particular, leaf springs  652  are oriented about 90 degrees different than leaf springs  606 . This results in a thick dimension of leaf springs  652  opposing rotation of an earpiece associated with pivot mechanism  650 .  FIG.  6 F  also shows flexible circuit  654  and board-to-board connector  656 . Flexible circuit can electrically couple a strain gauge positioned upon leaf spring  652  to a circuit board or other electrically conductive pathways on pivot mechanism  650 . In some embodiments, sensor data provided by the strain gauge can be configured to determine whether or not headphones associated with pivot mechanism  650  are being worn by a user of the headphones. Pivot mechanism  650  is also depicted including a portion  658  of a stem configured to attach pivot mechanism  650  to a headband. 
       FIG.  6 G  shows another pivot assembly  660  attached to earpiece housing  612  by fasteners  662  and bracket  663 . Pivot assembly  660  can include multiple helical springs  664  arranged side by side. In this way, helical coils  664  can act in parallel increasing the amount of resistance provided by pivot assembly  660 . Helical springs  664  are held in place and stabilized by pins  666  and  668 . Actuator  670  translates any force received from rotation of stem base  658  to helical springs  664 . In this way, helical springs  664  can establish a desired amount of resistance to rotation of stem base  658 . 
       FIGS.  6 H- 6 I  show pivot assembly  660  with one side removed in order to illustrate rotation of stem base  658  in different positions. In particular,  FIGS.  6 H- 6 I  shows how rotation of stem base  658  results in rotation of actuator  670  and compression of helical springs  664 . 
       FIG.  6 J  shows a cutaway perspective view of pivot assembly  660  disposed within earpiece housing  612 . In some embodiments, stem base  658  can include a bearing  674 , as depicted, to reduce friction between stem base  658  and actuator  670 .  FIG.  6 J  also shows how bracket  663  can define a bearing for securing pin  666  in place. Pins  666  and  668  are also shown defining flattened recesses for keeping helical springs  664  securely in place. In some embodiments, the flattened recess can include protrusions that extends into central openings of helical springs  664 . 
       FIGS.  6 K- 6 L  show partial cross-sectional side views of pivot assembly  660  positioned within earpiece housing with helical springs  664  in relaxed and compressed states. In particular, the motion undergone by actuator  670  when shifting from a first position in  FIG.  6 K  to a second position of maximum deflection is clearly depicted.  FIGS.  6 K and  6 L  also depict mechanical stop  676  which helps limit an amount of rotation earpiece housing can achieve relative to stem base. 
       FIGS.  6 M- 6 N  show side views of two different rotational positions of stem base  672  isolated from its pivot assembly. In particular two permanent magnets  678  and  680  are shown rigidly coupled to stem base  672 . Permanent magnets  678  and  680  emit magnetic fields with polarities oriented in opposing directions. Magnetic field sensor  682  is mounted to earpiece housing  612  such that magnetic field sensor  682  remains motionless relative to stem base  672  during rotation of stem base  672  about axis of rotation  684 . In this way, at a first position depicted in  FIG.  6 M , magnetic field sensor  682  is positioned proximate permanent magnet  680  and at a second position depicted in  FIG.  6 N , magnetic field sensor  682 . The opposing polarities of permanent magnets  678  and  682  allow magnetic field sensor  682  to distinguish between the two depicted positions. In some embodiments, the positions can vary by about 20 degrees; however, a total range of motions of stem base  672  can vary between about 10 and 30 degrees. In some embodiments, magnetic field sensor  682  can take the form of a magnetometer or a Hall Effect sensor. Depending on a sensitivity of magnetic field sensor  682 , magnetic field sensor  682  can be configured to measure an approximate angle of stem base  672  relative to earpiece housing  612 . For example, where the depicted rotational positions differ by 20 degrees an intermediate position of 10 degrees could be inferred by sensor readings from magnetic field sensor  682  where the magnetic field directions transition from one direction to another. In some embodiments, magnetic field sensor  682  can be configured to operate with only a single permanent magnet and be configured to determine rotational position of stem base  672  based solely on a magnetic field strength detected by magnetic field sensor  682 . It should be noted that in alternative embodiments magnetic field sensor  682  can be coupled to stem base  672  and permanent magnets  678  and  680  can be coupled to earpiece housing resulting in magnetic field sensor  682  moving within the earpiece housing. 
     Low Spring-Rate Band 
       FIG.  7 A  shows multiple positions of a spring band  700  suitable for use in a headband assembly. Spring band  700  can have a low spring rate that causes a force generated by the band in response to deformation of spring band  700  to change slowly as a function of displacement. Unfortunately, the low spring rate also results in the spring having to go through a larger amount of displacement before exerting a particular amount of force. Spring band  700  is depicted in different positions  702 ,  704 ,  706  and  708 . Position  702  can correspond to spring band  700  being in a neutral state at which no force is exerted by spring band  700 . At position  704 , a spring band  700  can begin exerting a force pushing spring band  700  back toward its neutral state. Position  706  can correspond to a position at which users with small heads bend spring band  700  when using headphones associated with spring band  700 . Position  708  can correspond to a position of spring band  700  in which the users with large heads bend spring band  700 . The displacement between positions  702  and  706  can be sufficiently large for spring band  700  to exert an amount of force sufficient to keep headphones associated with spring band  700  from falling off the head of a user. Further, due to the low spring rate the force exerted by spring band  700  at position  708  can be small enough so that use of headphones associated with spring band  700  is not high enough to cause a user discomfort. In general, the lower the spring rate of spring band  700 , the smaller the variation in force exerted by spring band  700 . In this way, use of a low spring-rate spring band  700  can allow headphones associated with spring band  700  to give users with different sized heads a more consistent user experience. 
       FIG.  7 B  shows a graph illustrating how spring force varies based on spring rate as a function of displacement of spring band  700 . Line  710  can represent spring band  700  having its neutral position equivalent to position  702 . As depicted, this allows spring band  700  to have a relatively low spring rate that still passes through a desired force in the middle of the range of motion for a particular pair of headphones. Line  712  can represent spring band  700  having its neutral position equivalent to position  704 . As depicted, a higher spring rate is required to achieve a desired amount of force being exerted in the middle of the desired range of motion. Finally, line  714  represents spring band  700  having its neutral position equivalent to position  706 . Setting spring band  700  to have a profile consistent with line  714  would result in no force being exerted by spring band  700  at the minimum position for the desired range of motion and over twice the amount of force exerted compared with spring band  700  having a profile consistent with line  710  at the maximum position. While configuring spring band  700  to travel through a greater amount of displacement prior to the desired range of motion has clear benefits when wearing headphones associated with spring band  700 , it may not be desirable for the headphones to return to position  702  when worn around the neck of a user. This could result in the headphones uncomfortably clinging to the neck of a user. 
       FIG.  8 A- 8 B  show a solution for preventing discomfort caused by headphones  800  utilizing a low spring-rate spring band from wrapping too tightly around the neck of a user. Headphones  800  include a headband assembly  802  joining earpieces  804 . Headband assembly  802  includes compression band  806  coupled to an interior-facing surface of spring band  700 .  FIG.  8 A  shows spring band  700  in position  708 , corresponding to a maximum deflection position of headphones  800 . The force exerted by spring band  700  can act as a deterrent to stretching headphones  800  past this maximum deflection position. In some embodiments, an exterior facing surface of spring band  700  can include a second compression band configured to oppose deflection of spring band  700  past position  708 . As depicted, knuckles  808  of compression band  806  serve little purpose when spring band is in position  708  on account of none of the lateral surfaces of knuckles  808  being in contact with adjacent knuckles  808 . 
       FIG.  8 B  shows spring band  700  in position  706 . At position  706 , knuckles  808  come into contact with adjacent knuckles  808  to prevent further displacement of spring band  700  towards position  704  or  702 . In this way, compression band  806  can prevent spring band  700  from squeezing the neck of a user of headphones  800  while maintaining the benefits of the low-spring rate spring band  700 .  FIGS.  8 C- 8 D  show how separate and distinct knuckles  808  can be arranged along the lower side of spring band  700  to prevent spring band  700  from returning past position  706 . 
       FIGS.  8 E- 8 F  show how the use of springs to control the motion of headband assembly  802  with respect to earpieces  804  can change the amount of force applied to a user by headphones  800  when compared to the force applied by spring band  700  alone.  FIG.  8 E  shows forces  810  exerted by spring band  700  and forces  812  exerted by springs controlling the motion of earpieces  804  with respect to headband assembly  802 .  FIG.  8 F  shows exemplary curves illustrating how forces  810  and  812  supplied by at least two different springs can vary based on spring displacement. Force  810  does not begin to act until just prior to the desired range of motion on account of the compression band preventing spring band  700  from returning all the way to a neutral state. For this reason, the amount of force imparted by force  810  begins at a much higher level, resulting in a smaller variation in force  810 .  FIG.  8 F  also illustrates force  814 , the result of forces  810  and  812  acting in series. By arranging the springs in series, a rate at which the resulting force changes as headphones  800  change shape to accommodate the size of a user&#39;s head is reduced. In this way, the dual spring configuration helps to provide a more consistent user experience for a user base that includes a great diversity of head shapes. 
       FIGS.  8 G- 8 H  show another way in which to limit the range of motion of a pair of headphones  850  using a low spring-rate band  852 .  FIG.  8 G  shows cable  854  in a slack state on account of earpieces  856  being pulled apart. The range of motion of low spring-rate band  852  can be limited by cable  854  achieving a similar function to the function of compression band  806 , engaging as a result of function of tension instead of compression. Cable  854  is configured to extend between earpieces  856  and is coupled to each of earpieces  856  by anchoring features  858 . Cable  854  can be held above low spring-rate band  852  by wire guides  860 . Wire guides  860  can be similar to wire guides  210  depicted in  FIGS.  2 A- 2 G , with the difference that wire guides  860  are configured to elevate cable  854  above low spring-rate band  852 . Bearings of wire guides  860  can prevent cable  854  from catching or becoming undesirably tangled. It should be noted that cable  854  and low spring-rate band  852  can be covered by a cosmetic cover. It should also be noted that in some embodiments, cable  854  could be combined with the embodiments shown in  FIGS.  2 A- 2 G  to produce headphones capable of synchronizing earpiece position and controlling the range of motion of the headphones. 
       FIG.  8 H  shows how when earpieces  856  are brought closer together cable  854  tightens and eventually stops further movement of earpieces  856  closer together. In this way, a minimum distance  862  between earpieces  856  can be maintained that allows headphones  850  to be worn around the neck of a broad population of users without squeezing the neck of the user too tightly. 
     Left/Right Ear Detection 
       FIG.  9 A  shows an earpiece  902  of headphones positioned over an ear  904  of a user. Earpiece  902  includes at least proximity sensors  906  and  908 . Proximity sensors  906  and  908  are positioned within a recess defined by earpiece  902  resulting in detectably different readings being returned by proximity sensors  906  and  908  depending on which ear earpiece  902  is positioned over. This is possible due to the asymmetric geometry of most user&#39;s ears. In some embodiments, proximity sensor  906  includes a light emitter configured to emit infrared light and an optical receiver configured to detect the emitted light reflecting off ear  904  of the user. A processor incorporated within or electrically coupled to proximity sensor  906  can be configured to determine a distance between proximity sensor  906  and proximate portions of ear  904  by measuring the amount of time it takes for infrared pulses emitted by the light emitter to return back to the light detector. In some embodiments, proximity sensor  906  can also be configured to map a contour of a portion of the ear. This can be accomplished with multiple emitters configured to emit light of different frequencies in different directions. Sensor readings collected by one or more optical receivers configured to detect and distinguish the different frequencies can then be used to determine a distance between proximity sensor  906  and different locations on the ear. In some embodiments, proximity sensors  906  can be distributed around a circumference of earpiece  902  when even more detail about the shape and position of the ear with respect to the earpiece is desired. For example, in some embodiments, it may be desirable to in addition to identifying which ear the earpiece is positioned upon, identify a rotational position of the ear with respect to the earpiece. Sensor readings could be of sufficiently high quality to identify certain features of ear  904  such as for example an earlobe or a pinna. In some embodiments and as depicted an angle at which infrared light is emitted from proximity sensor  908  can be different than an angle at which infrared light is emitted from proximity sensor  906 . In this way, a likelihood of detecting an ear or the side of a user&#39;s head can be increased. As depicted, proximity sensor  908  would be able to achieve earlier detection due to it being pointed farther outside of the interior of earpiece  902 . Proximity sensor  906  with its shallower angle would be able to cover a larger area of ear  904  of the user. In some embodiments, a capacitive sensor array can be positioned just beneath the surface of earpiece  902  and be configured to identify protruding features of the ear that contact or are in close proximity to surface  912  of earpiece  902 . 
       FIG.  9 B  shows positions of capacitive sensors  910  beneath surface  912  and proximate ear contours  914  associated with ear  904 . Ear contours  914  represent those contours of ear  904  most likely to protrude closest to the array of capacitive sensors  910 . Capacitive sensors  910  can be configured to identify portions of the detected contours of ear  904  to determine which ear earpiece  902  is positioned upon as well as any rotation of earpiece  902  relative to ear  904 .  FIG.  9 B  also indicates how both surface  912  and the array of capacitive sensors  910  define openings  916  or perforations through which audio waves are able to pass substantially unattenuated. While the array of capacitive sensors  910  are shown disposed beneath only a central portion of surface  912 , it should be appreciated that in some embodiments the array of capacitive sensors  912  could be arranged in different patterns resulting in a greater or smaller amount of coverage. For example, in some embodiments capacitive sensors  910  can be distributed across a majority of surface  912  in order to more completely characterize the shape and orientation of ear  904 . In some embodiments, the location and orientation data captured by capacitive sensors  910  and/or proximity sensors  906 / 908  can be used to optimize audio output from speaker disposed within earpiece  902 . For example, an earpiece with an array of audio drivers could be configured to actuate only those audio drivers centered upon or proximate ear  904 . 
       FIG.  10 A  shows a top view of an exemplary head of a user  1000  wearing headphones  1002 . Earpieces  1004  are depicted on opposing sides of user  1000 . A headband joining earpieces  1004  is omitted to show the features of the head of user  1000  in greater detail. As depicted, earpieces  1004  are configured to rotate about a yaw axis so they can be positioned flush against the head of user  1000  and oriented slightly towards the face of user  1000 . In a study performed upon a large group of users it was found that on average, earpieces  1004  when situated over the ears of a user were offset above the x-axis as depicted. Furthermore, for over 99% of users the angle of earpieces  1004  with respect to the x-axis was above the x-axis. This means that only a statistically irrelevant portion of users of headphones  1002  would have head shapes causing earpieces  1004  to be oriented forward of the x-axis.  FIG.  10 B  shows a front view of headphones  1002 . In particular,  FIG.  10 B  shows yaw axes of rotation  1006  associated with earpieces  1004  and how earpieces  1004  are both oriented toward the same side of headband  1008  joining earpieces  1004 . 
       FIGS.  10 C- 10 D  show top views of headphones  1002  and how earpieces  1004  are able to rotate about yaw axes of rotation  1006 .  FIGS.  10 C- 10 D  also show earpieces  1004  being joined together by headband  1008 . Headband  1008  can include yaw position sensors  1010 , which can be configured to determine an angle of each of earpieces  1004  with respect to headband  1008 . The angle can be measured with respect to a neutral position of earpieces with respect to headband  1008 . The neutral position can be a position in which earpieces  1004  are oriented directly toward a central region of headband  1008 . In some embodiments, earpieces  1004  can have springs that return earpieces  1004  to the neutral position when not being acted upon by an external force. The angle of earpieces relative to the neutral position can change in a clockwise direction or counter clockwise direction. For example, in  FIG.  10 C  earpiece  1004 - 1  is biased about axis of rotation  1006 - 1  in a counter clockwise direction and earpiece  1004 - 2  is biased about axis of rotation  1006 - 2  in a clockwise direction. In some embodiments, sensors  1010  can be time of flight sensors configured to measure angular change of earpieces  1004 . The depicted pattern associated and indicated as sensor  1010  can represent an optical pattern allowing accurate measurement of an amount of rotation of each of the earpieces. In other embodiments, sensors  1010  can take the form of magnetic field sensors or Hall Effect sensors as described in conjunction with  FIGS.  5 B and  6 E . In some embodiments, sensors  1010  can be used to determine which ear each earpiece is covering for a user. Because earpieces  1004  are known to be oriented behind the x-axis for almost all users, when sensors  1010  detect both earpieces  1004  oriented to towards one side of the x-axis headphones  1002  can determine which earpieces are on which ear. For example,  FIG.  10 C  shows a configuration in which earpiece  1004 - 1  can be determined to be on the left ear of a user and earpiece  1004 - 2  is on the right ear of the user. In some embodiments, circuitry within headphones  1002  can be configured to adjust the audio channels so the correct channel is being delivered to the correct ear. 
     Similarly,  FIG.  10 D  shows a configuration in which earpiece  1004 - 1  is on the right ear of a user and earpiece  1004 - 2  is on the left ear of a user. In some embodiments, when earpieces are not oriented towards the same side of the x-axis, headphones  1002  can request further input prior to changing audio channels. For example, when earpieces  1004 - 1  and  1004 - 2  are both detected as being biased in a clockwise direction, a processor associated with headphones  1002  can determine headphones  1002  are not in current use. In some embodiments, headphones  1002  can include an override switch for the case where the user wants to flip the audio channels independent of the L/R audio channel routing logic associated with yaw position sensors  1010 . In other embodiments, another sensor or sensors can be activated to confirm the position of headphones  1002  relative to the user. 
       FIGS.  10 E- 10 F  show flow charts describing control methods that can be carried out when roll and/or yaw of the earpieces with respect to the headband is detected.  FIG.  10 E  shows a flow chart that describes a response to detection of rotation of earpieces with respect to a headband of headphones about a yaw axis. The yaw axes can extend through a point located near the interface between each earpiece and the headband. When the headphones are being used by a user, the yaw axes can be substantially parallel to a vector defining the intersection of the sagittal and coronal anatomical planes of the user. At  1052 , rotation of the earpieces about the yaw axes can be detected by a rotation sensor associated with a pivot mechanism. In some embodiments, the pivot mechanism can be similar to pivot mechanism  500  or pivot mechanism  600 , which depict yaw axes  506  and  605 . At  1054 , a determination can be made regarding whether a threshold associated with rotation about the yaw axis has been exceeded. In some embodiments, the yaw threshold can be met anytime the earpieces pass through a position where the ear-facing surfaces of the two earpieces can be facing directly towards one another. At  1056 , in the case where at least one of the earpieces passes through the threshold and both earpieces are determined to be oriented in the same direction, the audio channels being routed to the two earpieces can be swapped. In some embodiments, the user can be notified of the change in audio channels. In some embodiments, an amount of roll detected by the pivot mechanism can be factored into a determination of how to assign the audio channels. 
       FIG.  10 F  shows a flow chart that describes a method for changing the operating state of headphones based on sensor readings from one or more sensors of the headphones. At  1062 , prior to a final packaging operation headphones can be put in a hibernating state in which little or no power is expended. In this way, headphones  1062  can have a substantial amount of battery power left on delivery. Delivery personnel could carry out a special procedure in order to remove the headphones from the hibernation state. For example, a data connector engaged with a charging port of the headphones could be removed triggering removal from the hibernation state. At  1063 , the headphones can be in a suspended state whenever they have not been used for a threshold amount of time. In the suspended state sensor polling rates can be substantially reduced to further conserve power. In some embodiments, the headphones may take longer than normal to identify a user attempting to use the headphones. At  1064 , a strain gauge or capacitive sensor can be used to identify placement of the headphones on a user&#39;s head. In some embodiments, the method can include returning to the suspended state at  1063  when a motion time out occurs or a strain gauge indicates the headphones are not being worn. At  1065 , capacitive or proximity type sensors can be used to sense the presence and/or orientation of ears within the earpieces. At  1066 , once an orientation of the headphones on the user&#39;s head is identified, input controls can be activated. At  1067 , media playback can begin by routing audio channels received wirelessly or via a wired cable to corresponding earpieces. Removing headphones from a user&#39;s ears can result in a return to  1064  at which time the sensors can go back through the various steps to correctly identify earpiece locations and orientations. 
       FIG.  10 G  shows a system level block diagram of a computing device  1070  that can be used to implement the various components described herein, according to some embodiments. In particular, the detailed view illustrates various components that can be included in headphones  1002  illustrated in  FIGS.  10 A- 10 D . As shown in  FIG.  10 G , the computing device  1070  can include a processor  1072  that represents a microprocessor or controller for controlling the overall operation of computing device  1070 . The computing device  1070  can include first and second earpieces  1074  and  1076  joined by a headband assembly, the earpieces including speakers for presenting media content to the user. Processor  1072  can be configured to transmit first and second audio channels to first and second earpieces  1074  and  1076 . In some embodiments, first orientation sensor(s)  1078  can be configured to transmit orientation data of first earpiece  1074  to processor  1072 . Similarly, second orientation sensor(s)  1080  can be configured to transmit orientation data of second earpiece  1076  to processor  1072 . Processor  1072  can be configured to swap the 1st Audio Channel with the 2nd Audio Channel in accordance with information received from first and second orientation sensors  1078  and  1080 . A data bus  1082  can facilitate data transfer between at least battery/power source  1084 , wireless communications circuitry  1084 , wired communications circuitry  1082  computer readable memory  1080  and processor  1072 . In some embodiments, processor  1072  can be configured to instruct battery/power source  1084  in accordance with information received by first and second orientation sensors  1078  and  1080 . Wireless communications circuitry  1086  and wired communications circuitry  1088  can be configured to provide media content to processor  1072 . In some embodiments, processor  1072 , wireless communications circuitry  1086  and wired communications circuitry  1088  can be configured to transmit and receive information from computer-readable memory  1090 . Computer readable memory  1090  can include a single disk or multiple disks (e.g. hard drives) and includes a storage management module that manages one or more partitions within computer readable memory  1090 . 
     Foldable Headphones 
       FIGS.  11 A- 11 B  show headphones  1100  having a deformable form factor.  FIG.  11 A  shows headphones  1100  including deformable headband assembly  1102 , which can be configured to mechanically and electrically couple earpieces  1104 . In some embodiments, earpieces  1104  can be ear cups and in other embodiments, earpieces  1104  can be on-ear earpieces. Deformable headband assembly  1102  can be joined to earpieces  1104  by foldable stem regions  1106  of headband assembly  1102 . Foldable stem regions  1106  are arranged at opposing ends of deformable band region  1108 . Each of foldable stem regions  1106  can include an over-center locking mechanism that allows each of earpieces  1104  to remain in a flattened state after being rotated against deformable band region  1108 . The flattened state refers to the curvature of deformable band region  1108  changing to become flatter than in the arched state. In some embodiments, deformable band region  1108  can become very flat but in other embodiments the curvature can be more variable (as shown in the following figures). The over-center locking mechanism allows earpieces  1104  to remain in the flattened state until a user rotates the over-center locking mechanism back away from deformable band region  1108 . In this way, a user need not find a button to change the state, but simply perform the intuitive action of rotating the earpiece back into its arched state position. 
       FIG.  11 B  shows one of earpieces  1104  rotated into contact with deformable band region  1108 . As depicted, rotation of just one of earpieces  1104  against deformable band region  1108  causes half of deformable band region  1108  to flatten.  FIG.  11 C  shows the second one of earpieces rotated against deformable band region  1108 . In this way, headphones  1100  can be easily transformed from an arched state (i.e.  FIG.  11 A ) to a flattened state (i.e.  FIG.  11 C ). In the flattened state headphones, the size of headphones  1100  can be reduced to a size equivalent to two earpieces arranged end to end. In some embodiments, deformable band region can press into cushions of earpieces  1104 , thereby substantially preventing headband assembly  1102  from adding to the height of headphones  1100  in the flattened state. 
       FIGS.  11 D- 11 F  show how earpieces  1104  of headphones  1150  can be folded towards an exterior-facing surface of deformable band region  1108 .  FIG.  11 D  shows headphones  11 D in an arched state. In  FIG.  11 E , one of earpieces  1104  is folded towards the exterior-facing surface of deformable band region  1108 . Once earpiece  1104  is in place as depicted, the force exerted in moving earpiece  1104  to this position can place one side of deformable headband assembly  1102  in a flattened state while the other side stays in the arched state. In  FIG.  11 F , the second earpiece  1104  is also shown folded against the exterior-facing 
       FIGS.  12 A- 12 B  show a headphones embodiment in which the headphones can be transitioned from an arched state to a flattened state by pulling on opposing ends of a spring band.  FIG.  12 A  shows headphones  1200 , which can be, for example, headphones  1100  shown in  FIG.  11   , in a flattened state. In the flattened state, earpieces  1104  are aligned in the same plane so that each of earpads  1202  face in substantially the same direction. In some embodiments, headband assembly  1102  contacts opposing sides of each of earpads  1202  in the flattened state. Deformable band region  1108  of headband assembly  1102  includes spring band  1204  and segments  1206 . Spring band  1204  can be prevented from returning headphones  1200  to the arched state by locking components of foldable stem regions  1106  exerting pulling forces on each end of spring band  1204 . Segments  1206  can be connected to adjacent segments  1206  by pins  1208 . Pins  1208  allow segments to rotate relative to one another so that the shape of segments  1206  can be kept together but also be able to change shape to accommodate an arched state. Each of segments  1206  can also be hollow to accommodate spring band  1204  passing through each of segments  1206 . A central or keystone segment  1206  can include fastener  1210 , which engages the center of spring band  1204 . Fastener  1210  isolates the two side of spring band  1204  allowing for earpieces  1104  to be sequentially rotated into the flattened state as depicted in  FIG.  11 B . 
       FIG.  12 A  also shows each of foldable stem regions  1106  which include three rigid linkages joined together by pins that pivotally couple upper linkage  1212 , middle linkage  1214  and lower linkage  1216  together. Motion of the linkages with respect to each other can also be at least partially governed by spring pin  1218 , which can have a first end coupled to a pin  1220  joining middle linkage  1214  to lower linkage  1216  and a second end engaged within a channel  1222  defined by upper linkage  1212 . The second end of spring pin  1218  can also be coupled to spring band  1204  so that as the second end of spring pin  1218  slides within channel  1222  the force exerted upon spring band  1204  changes. Headphones  1200  can snap into the flattened state once the first end of spring pin  1218  reaches an over-center locking position. The over-center locking position keeps earpiece  1104  in the flattened position until the first end of spring pin  1218  is moved far enough to be released from the over-center locking position. At that point, earpiece  1104  returns to its arched state position. 
       FIG.  12 B  shows headphones  1200  arranged in an arched state. In this state, spring band  1204  is in a relaxed state where a minimal amount of force is being stored within spring band  1204 . In this way, the neutral state of spring band  1204  can be used to define the shape of headband assembly  1102  in the arched state when not being actively worn by a user.  FIG.  12 B  also shows the resting state of the second end of spring pins  1218  within channels  1222  and how the corresponding reduction in force on the end of spring band  1204  allows spring band  1204  to help headphones  1200  assume the arched state. It should be noted that while substantially all of spring band  1204  is depicted in  FIGS.  12 A- 12 B  that spring band  1204  would generally be hidden by segments  1206  and upper linkages  1212 . 
       FIGS.  12 C- 12 D  show side views of foldable stem region  1106  in arched and flattened states, respectively.  FIG.  12 C  shows how forces  1224  exerted by spring pin  1218  operate to keep linkages  1212 ,  1214  and  1216  in the arched state. In particular, spring pin  1218  keeps the linkages in the arched state by preventing upper linkage  1212  from rotating about pin  1226  and away from lower linkage  1216 .  FIG.  12 D  shows how forces  1228  exerted by spring pin  1218  operate to keep linkages  1212 ,  1214  and  1216  in the flattened state. This bi-stable behavior is made possible by spring pin  1218  being shifted to an opposite side of the axis of rotation defined by pin  1226  in the flattened state. In this way, linkages  1212 - 1216  are operable as an over-center locking mechanism. In the flattened state, spring pin  1218  resists transitioning the headphones from moving from the flattened state to the arched state; however, a user exerting a sufficiently large rotational force on earpiece  1104  can overcome the forces exerted by spring pin  1218  to transition the headphones between the flat and arched states. 
       FIG.  12 E  shows a side view of one end of headphones  1200  in the flattened state. In this view, earpads  1202  are shown with a contour configured to conform to the curvature of the head of a user. The contour of earpads  1202  can also help to prevent headband assembly  1102  and particularly segments  1206  making up headband assembly  1102  from protruding substantially farther vertically than earpads  1202 . In some embodiments, the depression of the central portion of earpads  1202  can be caused at least in part by pressure exerted on them by segments  1206 . 
       FIGS.  13 A- 13 B  show partial cross-sectional views of headphones  1300 , which use an off-axis cable to transition between an arched state and a flattened state.  FIG.  13 A  shows a partial cross-sectional view of headphones  1300  in an arched state. Headphones  1300  differ from headphones  1200  in that when earpieces  1104  are rotated towards headband assembly  1102  a cable  1302  is tightened in order to flatten deformable band region  1108  of headband assembly  1102 . Cable  1302  can be formed from a highly elastic cable material such as Nitinol™, a Nickel Titanium alloy. Close-up view  1303  shows how deformable band region  1108  can include many segments  1304  that are fastened to spring band  1204  by fasteners  1306 . In some embodiments, fasteners  1306  can also be secured to spring band  1204  by an O-ring to prevent any rattling of fasteners  1306  while using headphones  1300 . A central one of segments  1304  can include a sleeve  1308  that prevents cable  1302  from sliding with respect to the central one of segments  1304 . The other segments  1304  can include metal pulleys  1310  that keep cable  1302  from experiencing substantial amounts of friction as cable  1302  is pulled on to flatten headphones  1300 .  FIG.  13 A  also shows how each end of cable  1302  is secured to a rotating fastener  1312 . As foldable stem region  1106  rotates, rotating fasteners  1312  keeps the ends of cable  1302  from twisting. 
       FIG.  13 B  shows a partial cross-sectional view of headphones  1300  in a flattened state. Rotating fasteners  1312  are shown in a different rotational position to accommodate the change in orientation of cable  1302 . The new location of rotating fasteners  1312  also generates an over-center locking position that prevents headphones  1300  from being inadvertently returned to the arched state as described above with respect to headphones  1200 .  FIG.  13 B  also shows how the curved geometry of each of segments  1304  allows segments  1304  to rotate with respect to one another in order to transition between the arched and flattened states. In some embodiments, cable  1302  can also be operative to limit a range of motion of spring band  1204  similar in some ways to the embodiment shown in  FIGS.  9 A- 9 B . Headphones  1300  also include input panels  1314  affixed to an outward facing surface of headphones  1300  in the flattened state. Input panels  1314  can define a touch sensitive input surface allowing users to input operating instructions into headphones  1300  when headphones  1300  are in the flattened state. For example, a user might wish to continue media playback with headphones  1300  in the flattened state. Easy access to input panels  1314  would make controlling operation of headphones  1300  in this state straightforward and convenient. 
       FIG.  14 A  shows headphones  1400  that are similar to headphones  1300 . In particular, headphones  1400  also use cable  1302  to flatten deformable band region  1108 . Furthermore, a central portion of cable  1302  is retained by the central segment  1304 . In contrast, lower linkage  1216  of foldable stem region  1106  is shifted upward with respect to lower linkage  1216  depicted in  FIG.  12 A . When earpiece  1104  is rotated about axis  1402  towards deformable band region  1108 , spring pin  1404  is configured to elongate as shown in  FIG.  14 B  during a first portion of the rotation. In some embodiments, elongation of spring pin  1404  can allow earpiece to rotate about 30 degrees from an initial position. Once spring pins  1404  reach their maximum length further rotation of earpieces  1104  about axes  1402  results in cable  1302  being pulled, which causes deformable band region  1108  to change from an arched geometry to a flat geometry as shown in  FIG.  14 C . The delayed pulling motion changes the angle from which cable  1302  is initially pulled. The changed initial angle can make it less likely for cable  1302  to bind when transitioning headphones  1400  from the arched state to the flattened state. 
       FIGS.  15 A- 15 F  show various views of headband assembly  1500  from different angles and in different states. Headband assembly  1500  has a bi-stable configuration that accommodates transitioning between flattened and arched states.  FIGS.  15 A- 15 C  depict headband assembly  1500  in an arched state. Bi-stable wires  1502  and  1504  are depicted within a flexible headband housing  1506 . Headband housing can be configured to change shape to accommodate at least the flattened and arched states. Bi-stable wires  1502  and  1504  extend from one end of headband housing  1506  to another and are configured to apply a clamping force through earpieces attached to opposing ends of headband assembly  1500  to a user&#39;s head to keep an associated pair of headphone securely in place during use.  FIG.  15 C  in particular shows how headband housing  1506  can be formed from multiple hollow links  1508 , which can be hinged together and cooperatively form a cavity within which bi-stable wires  1502  are able to transition between configurations corresponding to the arched and flattened states. Because links  1508  are only hinged on one side, the links are only able to move to the arched state in one direction. This helps avoid the unfortunate situation where headband assembly  1500  is bent the wrong direction, thereby position the earpieces in the wrong direction. 
       FIGS.  15 D- 15 F  show headband assembly in a flattened state. Because the ends of bi-stable wires  1502  and  1504  have passed an over-center point where the ends of wires  1502  and  1504  are higher than a central portion of bi-stable wires  1502  and  1504 , the bi-stable wires  1502  now help keep headband assembly  1500  in the flattened state. In some embodiments, bi-stable wires  1502  can also be used to carry signals and/or power through headband assembly  1500  from one earpiece to another. 
       FIGS.  16 A- 16 B  show headband assembly  1600  in folded and arched states.  FIG.  16 A  shows headband assembly  1600  in the arched state. Headband assembly, similarly to the embodiment shown in  FIGS.  15 C and  15 F  includes multiple hollow links  1602  that cooperatively form a flexible headband housing that define an interior volume. Passive linkage hinge  1604  can be positioned within a central portion of the interior volume and link bi-stable elements  1606  together.  FIG.  16 A  shows bi-stable elements  1606  and  16008  in arched configurations that resist forces acting to squeeze opposing sides of headband assembly  1600 . Once opposing sides of headband assembly  1600  are pushed together, in the directions indicated by arrows  1610  and  1612 , with enough force to overcome the resistance forces generated by bi-stable elements  1606  and  1608 , headband assembly  1600  can transition from the arched state depicted in  FIG.  16 A  to the folded state depicted in  FIG.  16 B . Passive linkage hinge  1604  accommodates headphone assembly  1600  being folding around a central region  1614  of headband assembly  1600 .  FIG.  16 B  shows how passive linkage hinge  1604  bends to accommodate the folded state of headband assembly  1600 . Bi-stable elements  1606  and  1608  are shown configured in folded configurations in order to bias the opposing sides of headband assembly  1600  toward one another, thereby opposing an inadvertent change in state. The folded configuration, depicted in  FIG.  16 B , has the benefit of taking up a substantially smaller amount of space by allowing the open area defined by headband assembly  1600  for accommodating the head of a user to be collapsed so that headband assembly  1600  can take up less space when not in active use. 
       FIGS.  17 - 18    show various views of foldable headphones  1700 . In particular,  FIG.  17    shows a top view of headphones  1700  in a folded state. Headband  1702 , which extends between earpieces  1704  and  1706 , includes wires  1708  and springs  1710 . In the depicted folded state, wires  1708  and spring  1710  are straight and in a relaxed state or neutral state.  FIG.  18    shows a side view of headphones  1700  in an arched state. Headphones  1700  can be transitioned from the folded state depicted in  FIG.  17    to the arched state depicted in  FIG.  18    by rotating earpieces  1704  and  1706  away from headband  1702 . Earpieces  1704  and  1706  each include an over-center mechanism  1802  that applies tension to the ends of wires  1708  to keep wires  1708  in tension in order to maintain an arched state of headband  1702 . Wires  1708  help maintain the shape of headband  1702  by exerting forces at multiple locations along springs  1710  through wire guides  1804 , which are distributed at regular intervals along headband  1702 . 
     Telescoping Stem Assembly 
       FIG.  19    shows one side of a headband housing  1902  as well as telescoping member  1904  extending from the end of headband housing  1902 . Headband housing  1902  can be configured to accommodate telescoping motion of telescoping member  1904 . Headband housing  1902  defines multiple channels  1906 , which help guide spring fingers  1908  associated with telescoping member  1904  as telescoping member  1904  slides into and out of lower headband housing  1902 .  FIG.  19    also depicts a portion of synchronization cable  1910  visible through channel  1906  and coiled within headband housing  1902 . The coiled configuration of synchronization cable  1910  allows synchronization cable  1910  to accommodate the changes in length caused by telescoping of telescoping member  1904  relative to headband housing  1902 . 
       FIG.  20 A  shows an exploded view of the side of headband housing  1902  depicted in  FIG.  19   . In particular, headband housing  1902  is depicted including upper housing component  2002  and lower housing component  2004 . Lower housing component  2004  is configured to receive telescoping member  1904 . Lower housing component  2004  is depicted defining multiple channels  1906  and an annular bushing  2006  is disposed within one end of lower housing component  2004  and configured to control the motion of telescoping member  1904  relative to lower housing component  2004  by generating friction during movement of telescoping member  1904 .  FIG.  20 A  also depicts spring member  2008  as a single piece that includes multiple spring fingers  2010  configured to engage channels  1906 . 
       FIG.  20 B  shows a cross-sectional view of a first end of lower housing component  2004  in accordance with section line F-F. Lower housing component  2004  is depicted engaged with telescoping member  1810  and bushing  2012  is positioned within telescoping member  1810 . One of spring fingers  2008  is shown engaged within channel  1906  of lower housing component  2004 . In some embodiments, channel  1906  does not extend entirely through a wall of lower housing component  2004  as depicted in  FIG.  20 C . This allows spring finger  2008  to be engaged within channel  1906  without it being cosmetically visible from an exterior of lower housing component  2004 . 
       FIG.  20 C  shows a cross-sectional view of a second end of lower housing component  2004  in accordance with section line G-G. The second end of lower housing component  2004  is depicted engaged with upper housing component  2002 . Synchronization cable  1910  is shown extending through an opening defined by both upper housing component  2002  and lower housing component  2004 . 
       FIG.  20 D  shows a perspective view of bushing  2006 , which defines multiple finger channels  2012  spaced radially around an interior-facing surface of bushing  2006 . Finger channels  2012  can be configured to align spring fingers  2010  with finger channels  2012  of lower housing component  2004 . 
       FIG.  21 A  shows a perspective view of spring member  2014  and one end of telescoping member  1810 . As depicted, spring member  2014  includes three spring fingers  2008 . Each of spring fingers  2008  includes a locking feature  2102  configured to prevent disengagement of spring member  2014  from telescoping member  1810 . Telescoping member  1810  defines a set of corresponding openings  2104  and  2106  divided by a bridging member  2108 . When spring fingers  2008  are engaged within openings  2104  a length of opening  2104  allows each of spring fingers  2008  to be deflected through openings  2104  so that telescoping member  1810  can be inserted into lower housing component  2004 . 
       FIG.  21 B  shows spring fingers  2008  engaged within openings  2104  and  FIG.  21 C  shows spring fingers  2008  engaged within openings  2106 . When locking features  2102  are engaged within openings  2106 , spring member  2014  cannot be removed and remain engaged within channels  1906 . Furthermore, bridging members  2108  prevent spring fingers  2008  from deflecting any farther into an interior volume  2110  defined by telescoping member  1810 . This keeps protruding portions of spring fingers  2008  securely engaged within corresponding channels  1906 . In some embodiments, spring member  2014  can be shifted from the position depicted in  FIG.  21 B  by pulling back on telescoping member  1810  once spring fingers  2008  are engaged within channels  1906 . In this way, spring fingers  2008  can be shifted from openings  2104  into openings  2106 . 
       FIGS.  21 D- 21 G  show various locking mechanisms positioned at an opening defined by lower housing component  2004  through which telescoping member  1810  extends.  FIGS.  21 D- 21 E  show locking mechanism  2112 . In  FIG.  21 D , when locking mechanism  2112  is turned in a first direction  2114 , telescoping member  1810  is able to be translated into or out of lower housing component  2004 , as indicated by two-sided arrow  2116 .  FIG.  21 E  shows how subsequently turning locking mechanism  2112  in direction  2118  causes a position of telescoping member  1810  to be fixed relative to lower housing component  2004 .  FIGS.  21 F- 21 G  show locking mechanism  2120 .  FIG.  21 F  shows how when locking mechanism  2120  is pulled away from lower housing component  2004  and toward telescoping member  1810  in direction  2122 , telescoping member  1810  is able to be translated into or out of lower housing component  2004 , as depicted by two-sided arrow  2124 .  FIG.  21 G  shows how when locking mechanism  2120  is then pushed toward lower housing component  2004  in direction  2126 , a position of telescoping member  1810  relative to lower housing component  2004  is fixed. 
     Anti-Buckling Assembly 
       FIGS.  22 A- 22 E  depict various extended and contracted coil configurations for a portion of synchronization cable  2010  disposed within lower housing component  2004 .  FIG.  22 A  shows a partial cross-sectional view of a portion of synchronization cable  2010  in a conventional helical coil configuration. Unfortunately, this configuration can be susceptible to individual loops  2202  shifting laterally when transitioning from the extended configuration  2204  to contracted configuration  2206  as depicted. Misalignment can lead to synchronization cable  2010  rubbing an interior of lower housing component  2004  and becoming frayed over time due to undesired friction inducing failure by fatigue of synchronization cable  2010 . 
       FIG.  22 B  shows how a cross-sectional shape of synchronization cable  2010  can be adjusted to include alignment features that help prevent loops  2212  of synchronization coil  2010  from becoming misaligned. In particular, opposing sides of loops  2212  can include alignment features having complementary geometries that help to self-align loops  2212  of synchronization coil  2010  when contracted, as depicted. 
       FIG.  22 C  shows how a cross-sectional shape of synchronization cable  2010  can be adjusted to include alignment features that help prevent loops  2222  of synchronization coil  2010  from becoming misaligned. In particular, opposing sides of loops  2222  can include alignment features taking the form of concave channels  2224  and convex ridges  2226  that help to self-align loops  2212  of synchronization coil  2010  when contracted, as depicted. 
       FIG.  22 D  shows how a cross-sectional shape of synchronization cable  2010  can be adjusted to include linking features that help prevent loops  2232  of synchronization coil  2010  from becoming misaligned. In particular, opposing sides of loops  2232  can include linking features taking the form of complementary hooks  2234  and convex ridges  2226  that help to self-align loops  2212  of synchronization coil  2010  when contracted, as depicted. The linking features also help to define a maximum amount of longitudinal extension of synchronization cable  2010 . 
       FIG.  22 E  shows another configuration in which synchronization cable  2010  can be prevented from becoming misaligned. By winding synchronization cable  2010  around a shaft  2342 , synchronization cable  2010  can be kept from becoming misaligned even though it is arranged as a helical coil. Shaft  2342  should be formed from a stiff material unlikely to go substantial amounts of bending, while also allowing for slight changes in curvature to accommodate motion of telescoping member  1810 . In some embodiments, shaft  2242  can be formed from NITINOL (a nickel-titanium alloy) wire. 
       FIG.  23 A  shows an exploded view of components associated with a data plug  2302 . In particular, data plug  2302 , which extends from one end of stem base  2304  is configured to engage a receptacle within telescoping member  1810 . Once engaged within the receptacle, data plug  2302  can be kept securely in place using threaded fastener  2306 , which is configured to engage a recess  2308  defined by a base portion of data plug  2302  through threaded opening  2310 . Seal rings  2312  can also be used to further secured data plug  2302  within telescoping member  1810 .  FIG.  23 B  shows telescoping member  1810  fully assembly with threaded fastener  2306  fully engaged within threaded opening  2310  in order to keep data plug  2302  securely positioned. 
       FIG.  23 C  shows a cross-sectional view of telescoping member  1810  in accordance with section line H-H of  FIG.  23 B . In particular,  FIG.  23 C  shows one end of data plug  2302  engaged within plug receptacle  2314 .  FIG.  23 C  also shows how threaded fastener cooperates with recess  2308  to keep data plug  2302  secured in place. A position of seal rings  2312  is also shown relative to data plug  2302 . It should be noted that in some embodiments data plug  2302  could be omitted in lieu of a cable terminating in a board to board connect that engages a printed circuit board within an associated earpiece of the headphones. 
       FIG.  23 D  shows a perspective view of a portion of data plug  2302 . In particular, the body of data plug  2302  has a stepped geometry and defines multiple glue channels  2316  spaced at a regular interval. In some embodiments, glue channels  2316  can be laser cut into an exterior side surface of the body of data plug  2302 .  FIG.  23 E  shows a cross-sectional side view of the portion of data plug  2302  and depicts multiple glue channels  2316  positioned on opposing sides of the body of data plug  2302 . 
       FIG.  23 F  shows data plug  2302  glued to stem base  2304 , which is in turn positioned within a recess  2318  defined by earpiece  2320 .  FIG.  23 G  shows a cross-sectional view of data plug  2302  disposed within a recess defined by stem base  2304 , which is in turn positioned within recess  2318  of earpiece  2320 .  FIG.  23 G  corresponds to section line I-I as depicted in  FIG.  23 F  and also shows how data plug  2302  is adhered to stem base  2304  by an adhesive layer  2322 . A strength of a bond formed by adhesive layer  2322  between stem base  2304  and the body of data plug  2302  is substantially increased due to adhesive layer  2322  being able to engage glue channels  2316 . In some embodiments, an interior-facing surface of stem base  2304  can also include glue channels similar to glue channels  2316  for even greater adhesion. In some embodiments, one or both of the surfaces contacting adhesive layer  2322  can be roughened, thereby increasing the surface energy of the surfaces and improving the strength of a resulting adhesive coupling.  FIG.  23 G  also depicts a data synchronization cable  2324  extending through channels defined by both data plug  2302  and stem base  2304 . 
     Earpad Configurations and Optimization 
       FIG.  24 A  shows perspective views of earpiece  2402  and earpad  2404 . Earpad  2404  is shown having a planar shape illustrating how the side of a user&#39;s head  2406  is anything but flat. One reason most earpads are quite robust in thickness is to accommodate the cranial contours of the side of a user&#39;s head. The dashed arrows depicted in  FIG.  24 A  illustrate the variance in distance earpads need to overcome to conform with the cranial contours. 
       FIG.  24 B  shows how earpieces  2412  and  2414  of headphones  2410  can have thin earpads  2416  without sacrificing user comfort. Earpads  2416  can include a flexible substrate that allows for a predetermined amount of flexure to accommodate variations in cranial contours. Earpads  2416  can be coupled to earpiece yokes  2418  with two posts  2420  positioned in locations corresponding to normally low points on a user&#39;s head. In the depicted configuration, the portions of earpads  2416  encountering protruding cranial contours can bend back to prevent pressure points on a user&#39;s head. In this way, a substantial amount of weight and material cost can be saved since thinner pads can be utilized without sacrificing user comfort. 
       FIG.  24 C  shows how posts  2420  couple flexible substrate  2422  to earpiece yokes  2418 . Flexible substrate  2422  is formed from a substrate having a flexibility sufficient to allow for deformation of earpads  2416  mounted to flexible substrate  2422 . It should be noted that many components have been removed from earpiece  2414  in  FIG.  24 C  to clearly show how flexible substrate  2422  is connected to earpiece yoke  2418 .  FIG.  24 D  shows earpiece  2414  and an axis of rotation  2424  about which earpad  2416  is configured to bend to accommodate cranial contours of a user&#39;s head. Axis of rotation  2424  is defined by the locations at which posts  2420  attach to a rear-facing surface of flexible substrate  2422  and consequently earpad  2416 . 
       FIG.  24 E- 24 H  depict another earpiece in a configuration designed to account for cranial contours of a user&#39;s head.  FIG.  24 E  shows a side view of earpiece  2430 . Earpiece  2430  includes convex input panel  2432 , earpiece housing  2434  and earpad assembly  2436 . Convex input panel  2432  can be affixed to one side of earpiece housing  2434  and include sensors for receiving touch inputs to headphones associated with the earpiece.  FIG.  24 E  also depicts compressible earpad  2438  of earpad assembly  2436 . Compressible earpad  2438  can be formed from foam and have a substantially uniform thickness. By bending compressible earpad  2438  as depicted into a curved geometry a user-facing surface of earpad assembly  2436  can be shaped to match cranial contours of a user&#39;s head. 
       FIG.  24 F  shows a cross-sectional view of earpiece  2430  as well as a shape of a cavity  2440  for accommodating an ear  2442 . With headphones designs that are not configured to accommodating placing earpiece  2430  over either ear, speaker assembly  2444  can protrude into cavity  2440  without affecting the amount of space available for ear  2442 . In some embodiments, pushing speaker assembly  2444  forward in this manner can reduce the overall size of earpiece  2430 .  FIG.  24 F  also demonstrates how an undercut geometry of earpad  2438  allows earpiece  2430  to seal around a portion of the user&#39;s head closer to ear  2442 , thereby reducing the length of a perimeter of the portion earpad assembly  2436  contacting the head of the user. In some embodiments, this can improve passive noise isolation. Earpad  2438  can be covered by textile material  2446  to provide a pleasant feel to the portion of earpad assembly  2436  contacting the user. In some embodiments, various treatments can be applied to textile material  2446  to improve the acoustic isolation provided by textile material  2446 . For example, a heat treatment could be applied to at least the portion of textile material  2446  most likely to contact the user&#39;s head in order to reduce a pore size of textile material  2446 , thereby boosting acoustic resistance. 
       FIG.  24 G  shows a perspective view of earpiece  2430  and more clearly illustrates the varying curvature of earpad assembly  2436  around a periphery of earpad assembly  2436 . In particular, region  2448  of earpad assembly  2436  is configured to contact a portion of a user&#39;s head beneath and to the rear of the ear where the head starts to slope back toward the neck. For this reason, region  2448  protrudes substantially farther out from earpiece  2430  than any other portion of earpad assembly  2436 . To a somewhat lesser extent region  2450  of earpad assembly  2436  also protrudes away from earpiece  2430  to accommodate another low spot on a user&#39;s head generally located forward and slightly above the user&#39;s ear. 
       FIGS.  25 A- 25 C  show various views of another earpad configuration  2500  formed from multiple layers of material.  FIG.  25 A  shows an exploded view of earpad configuration  2500  that includes three different component layers, namely cushion  2502 , compliant structural layer  2504  and textile layer  2506 . In some embodiments, cushion  2502  can be formed from foam and shaped during a machining process, which will be described in greater detail below. Compliant structural layer  2504  can help define a shape of a periphery of cushion  2502 , while giving an exterior of the earpiece an amount of compliance. In some embodiments, compliant structural layer  2504  can be formed from an ethylene-vinyl acetate rubber blend. Textile layer  2506  can be formed from a sheet of fabric and includes multiple distinct regions  2508  and  2510 . Region  2510 , which makes up a majority of the fabric in direct contact with a user&#39;s head, can be heat treated to seal any gaps in the fabric in order to improve passive acoustic isolation. This can be particularly important with headphones with an active noise cancelling system as improved passive acoustic isolation reduces the amount of noise needing to be cancelled out by the active noise cancelling system. In some embodiments, region  2510  can be heat-treated so that its porosity is substantially smaller than the porosity of regions  2508 . Lower porosity textile materials are generally more effective at providing passive noise attenuation. 
       FIG.  25 B  shows how foam cushion  2502  along with compliant structural layer  2504  and textile layer  2506  can be formed around an electronics housing component  2512  defining an interior volume  2514  configured to accommodate various electrical components supporting playback of media files received by headphones associated with earpad configuration  2500 .  FIG.  25 B  also illustrates the importance of aligning textile layer  2506  with openings defined by electronics housing component  2512 , since opening  2516  of textile layer  2506  is configured to align with opening  2518  of electronics housing component  2512  to accommodate an I/O port or input control. Furthermore, opening  2520  may also need to be aligned with post  2522  of housing component  2512 . 
       FIG.  25 C  shows a cross-sectional side view of earpad configuration  2500 . In particular,  FIG.  25 C  shows how textile layer  2506  includes two regions  2508  positioned on different sides of heat-treated region  2510  and how compliant structural layer  2504  extends beneath region  2510  of textile layer  2506 .  FIG.  25 D  shows how heat-treated regions  2510  of textile layer  2506  are in direct contact with the side of a user&#39;s head when the headphones are in active use. In this way, an effective barrier is formed by heat-treated regions  2510  against the passage of audio waves between the user&#39;s head and earpad configuration  2500 , which would generally not be considered viable for a headphones using textile material to cover the earpads. While region  2510  is shown extending entirely across a surface contacting a user&#39;s face it should be understood that in certain embodiments, only a portion of the textile fabric contacting a user has undergone the heat treatment. 
       FIGS.  26 A- 26 B  show perspective views of earpad  2602 , which can be formed from a conformable material such as open cell foam. Conventional foam pads for headphones are formed from rectangular blocks and if formed using machining methods at all would be formed by a stamping process. By machining earpads  2602  from a larger block a precise three-dimensional shape can be achieved. Machining is also superior over performing injection since while these types of processes could include a mold to achieve a desired shape the surface consistency often is materially different due to the heating processes that take place during the molding process. For at least these reasons, performance of a machined foam as an earpad cushion is substantially better than the alternatives since it allows for a customized responsiveness to pressure and reducing the overall weight of each earpad cushion by allowing for unneeded portions of the foam to be easily cut away. As depicted, earpad  2602  has a gradual sloping geometry on both sides, as depicted by FIGS.  26 A- 26 B, that give earpad  2602  an undercut geometry helping to establish a desired firmness of earpad  2602 . 
       FIG.  26 C- 26 G  show various manufacturing operations for forming an earpad from a block of foam.  FIG.  26 C  shows open cell foam block  2604  once it is formed by an extrusion or molding process. In  FIG.  26 D , profile cutter  2606  and ball end mill  2608  are depicted forming opposing sides of earpad  2602  from foam block  2604 . In some embodiments, the cutting and milling process can be made more exact by first soaking foam block  2610  in water as shown in  FIG.  26 E  and then freezing foam block as shown in  FIG.  26 F . In some embodiments, when profile cutter  2606  and ball end mill  2608  are applied to frozen foam block  2610  the machining operations can be a little more accurate since the foam material is less likely to move and deform under an amount of pressure applied by the machining tools. While the annular earpad is depicted having a substantially rectangular cross-sectional geometry, the CNC process allows for a much broader variety of shapes. For example, tear-drop, circular, square, elliptical, polygonal and other cross-sectional geometries could be realized by varying the machining operations performed by profile cutter  2606  and ball end mill  2608 . Non-euclidian surface shapes such as spline geometries are also fully capable realization using the aforementioned machining technique. 
     Speaker Assembly 
       FIG.  27 A  shows a cross-sectional side view of an exemplary acoustic configuration within earpiece  2700  that could be applied with any of the previously described earpieces. The acoustic configuration includes speaker assembly  2702 , which includes diaphragm  2704  and electrically conductive coil  2706 , which is configured to receive electrical current for generating a shifting magnetic field that interacts with a magnetic field emitted by permanent magnets  2708  and  2710 , which causes diaphragm  2704  to oscillate and generate audio waves that exit earpiece assembly through perforated wall  2709 . In some embodiments, perforated wall  2709  can include an array of capacitive sensors as depicted in  FIGS.  9 A- 9 B . A hole can be drilled through a central region of permanent magnet  2708  to define an opening  2712  that puts a rear volume of air behind diaphragm  2704  in fluid communication with interior volume  2714  through mesh layer  2716 , thereby increasing the effective size of the back volume of speaker assembly  2702 . Interior volume  2714  extends all the way to air vent  2718 . Air vent  2718  can be configured to further increase an effective size of the rear volume of speaker assembly  2702 . For example, air vent  2718  can act as a bass reflex vent for augmenting performance of speaker assembly  2702 . The rear volume of speaker assembly  2702  can be further defined by speaker frame member  2720  and input panel  2722 . In some embodiments, input panel  2722  can be separated from speaker frame member  2720  by about 1 mm. Speaker frame member  2720  defines an opening  2724  that allows audio waves to travel through additional ducting that routes the rear volume. Glue channel  2726  is defined by protrusions  2728  of speaker frame member  2720 . 
       FIG.  27 B  shows an exterior of earpiece  2700  with input panel  2722  removed to illustrate the shape and size of the interior volume associated with speaker assembly  2702 . As depicted, a central portion of earpiece  2700  includes permanent magnets  2708  and  2710 . Speaker frame member  2720  includes a recessed region that defines interior volume  2714 . Interior volume  2714  can have a width of about 20 mm and a height of about 1 mm as depicted in  FIG.  27 A . At the end of interior volume  2714  is opening  2724  defined by speaker frame member  2720 , which is configured to allow the back volume to continue beneath glue channel  2726  and extend to air vent  2718 , which leads out of earpiece  2700 . 
       FIG.  27 C  shows a cross-sectional view of a microphone mounted within earpiece  2700 . In some embodiments, microphone  2730  is secured across an opening  3732  defined by speaker frame member  2720 . Opening  3732  is offset from microphone intake vent  2734 , preventing a user from seeing opening  2732  from the exterior of earpiece  2700 . In addition to providing a cosmetic improvement, this offset opening configuration also tends to reduce the occurrence of microphone  2730  picking up noise from air passing quickly by microphone intake vent  2734 . 
       FIG.  28    shows earpiece  2700  having input panel  2720 , which can form an exterior facing surface of earpiece  2700 . A touch sensitive region can be established by touch sensor  2802 , which can take the form of a flexible substrate affixed to an interior facing surface of input panel  2720 . The flexible substrate can define multiple notches  2804 , which function as strain relief features allowing the flexible substrate to conform to a concave shape of the interior-facing surface of input panel  2720 . Passive radiator  2806  is depicted adjacent to touch sensor  2802  and also affixed to the interior-facing surface of radio transparent input panel  2720 . Passive radiator  2806  can be formed from a stamped sheet of metal or be formed along a flexible printed circuit. This configuration prevents interference between passive radiator  2806  and touch sensor  2802 . Passive radiator  2806  can cooperate with internal antenna  2808 , which is also positioned within earpiece  2700 , to improve wireless performance. 
     Distributed Battery Configuration 
       FIGS.  29 A- 29 B  show perspective and cross-sectional views of an outline of earpiece  2900  illustrating a position of distributed battery assemblies  2902  and  2904  within earpiece  2900 . In particular,  FIG.  29 A  shows how battery assemblies  2902  and  2904  can be positioned on opposing sides of a housing of earpiece  2900 .  FIG.  29 B  shows a cross-sectional view of earpiece  2900  in accordance with section line J-J. Battery assemblies  2902  and  2904  can also be tilted diagonally with respect to an ear cavity defined by earpiece  2900 , as depicted in  FIG.  29 B , to maximize a size of an ear cavity  2906  defined by earpiece  2900 .  FIG.  29 C  shows how more than two discrete battery assemblies can be incorporated into a single earpiece housing. For example, three, four, five or six discrete battery assemblies could be distributed along a periphery of earpiece  2900  as is shown in  FIG.  29 C . In some embodiments, and as is shown in  FIG.  29 C  battery assemblies  2908 - 2914  have a curvature that follows a curvature of an outer periphery of the earpiece housing and more generally the space available within the earpiece housing. Each of the discrete battery assemblies can have their own input and output terminals configured to support operation of various components within earpiece  2900 . 
       FIG.  30 A  shows headphones  3000 , which include earpieces  3002  and  3004  joined together by headband  3006 . A central portion of headband  3006  has been omitted to focus on components within earpieces  3002  and  3004 . In particular, earpieces  3002  and  3004  can include a mix of Hall Effect sensors and permanent magnets. As depicted, earpiece  3002  includes permanent magnet  3008  and Hall Effect sensor  3010 . Permanent magnet  3008  generates a magnetic field extending away from earpiece  3002  with a South polarity. Earpiece  3004  includes Hall Effect sensor  3012  and permanent magnet  3014 . In the depicted configuration, permanent magnet  3008  is positioned to output a magnetic field sufficiently strong to saturate Hall Effect sensor  3012 . Sensor readings from Hall Effect sensor  3012  can be sufficient to cue headphones  3000  that headphones  3000  are not being actively used and could enter into an energy savings mode. In some embodiments, this configuration could also cue headphones  3000  that headphones  3000  were being positioned within a case and should enter a lower power mode of operation to conserve battery power. Flipping earpieces  3002  and  3004  180 degrees each would result in a magnetic field emitted by permanent magnet  3014  saturating Hall Effect Sensor  3010 , which would also allow the device to enter a low power mode. In some embodiments, it could be desirable to use an accelerometer sensor within one or both of earpieces  3002  to confirm that earpieces  3002  and  3004  are facing toward the ground before entering a lower power state as a user could desire to set earpieces  3002  and  3004  facing upward to operate headphones in an off the head configuration and in such a case audio playback should be continued. 
       FIG.  30 B  shows an exemplary carrying/storage case  3016  well suited for use with circumaural and supra-aural headphones designs. Case  3016  includes a recess  3018  to accommodate a headband assembly and two earpieces. The portions of recess  3018  that accommodate the earpieces can include protrusions  3020  and  3022 , which fill recesses of earpieces sized to accommodate the ear of a user.  FIG.  30 C  shows headphones  3000  positioned within recess  3018  and  FIG.  30 D  shows a cross-sectional view of earpiece  3002  in accordance with section line K-K of  FIG.  30 C .  FIG.  30 D  shows how protrusion  3020  include capacitive elements  3024  arranged along an upward-facing surface of protrusion  3020  in a predefined pattern. Consequently, when headphones  3000  are placed within case  3016  and capacitive sensors  3026  sense capacitive elements in that predefined pattern headphones  3000  can be configured to shut down or go into a lower power mode to conserve power. 
       FIG.  30 E  shows carrying case  3016  with headphones  3000  positioned therein. Headphones  3000  are depicted including ambient light sensor  3028 . In some embodiments, input from ambient light sensor  3028  can be used to determine when case  3016  is closed with headphones disposed within case  3016 . Similarly, when sensor readings from ambient light sensor  3028  indicate an amount of light consistent with carrying case  3016  opening, a processor within headphones  3000  can determine that carrying case  3016  has been opened. In some embodiments, when other sensors aboard headphones  3000  indicate headphones  3000  are positioned within a recess defined by carrying case  3016 , the sensor data from ambient light source  3028  can be sufficient to determine when carrying case  3016  is open or closed. Examples of other sensors include the capacitive sensors discussed in the text describing  FIGS.  30 B- 30 D . Other examples of sensors could take the form Hall Effect sensors  3030  disposed within earpieces  3002  and  3004  that could be configured to detect magnetic fields emitted by permanent magnets  3032  disposed within carrying case  3016 . In some embodiments, one or more of magnets  3032  can be configured to emit a magnetic field with one or more recognizable magnetic field characteristics. For example, the two depicted permanent magnets  3032  could have opposing polarities that interact with Hall Effect sensors  3030 . Furthermore, one or both of permanent magnets could have a particularly strong magnetic field or a customized magnetic field with a highly varied polarity. Inadvertently experiencing such a magnetic field outside the controlled environment of the case would be unlikely and consequently, headphones configured to enter a low power state in response would be unlikely to do so accidentally. This second set of sensor data provided by Hall Effect sensors  3030  could substantially reduce the incidence of sensor data from ambient light sensor  3028  mistakenly being correlated with case opening and closing events. The use of sensor readings from other types of sensors such as strain gauges, time of flight sensors and other headphone configuration sensors can also be used to make operating state determinations. Furthermore, depending on a determined operating state of headphones  3000  these sensors could be activated with varying frequency. For example, when carrying case  3016  is determined to be closed around headphones  3000  sensor readings can only be made at an infrequent rate, whereas in active use the sensors could operate more frequently. 
     Illuminated Button Assembly 
       FIGS.  31 A- 31 B  show an illuminated button assembly  3100  suitable for use with the described headphones.  FIG.  31 A  shows how illuminated button assembly  3100  includes button  3102  and illuminated window  3104 , which can be configured to identify an operating state of headphones. Button  3102  is electrically coupled with other components within headphones by flexible circuit  3106 . At least a portion of button assembly  3100  can be secured to a device housing by mounting bracket  3108 .  FIG.  31 B  shows a rear view of illuminated button assembly  3100 , and how mounting bracket  3108  can be configured to receive fasteners  3110  to secure illuminated button assembly to a device housing. 
       FIGS.  31 C- 31 D  show side views of illuminated button assembly  3100  in unactuated and actuated positions, respectively, within a device housing  3111 .  FIG.  31 C  shows how illuminated window  3104  of button  3102  can have a tapered shape that directs light emitted by any one of multiple illumination elements  3114 . Illuminated window  3104  can also include securing features  3112 , which protrude laterally from illuminated window  3104  to prevent illuminated window  3104  from becoming disengaged from button  3102 . Illumination elements  3114  can be positioned proximate a rear-facing surface of illuminated window  3104 . Illumination elements  3104  can each take the form of a light emitting diode (LED) surface mounted to flexible circuit  3106 . In some embodiments, each of illumination elements  3114  can be configured to emit light of a different color, thereby allowing the light received by illuminated window  3104  to be changed to reflect a status or operating state of the device associated with illumination button assembly  3100 . In some embodiments, illumination elements  3114  could include red, yellow and blue colors. Selective illumination of two or more of the different colors at varying intensity levels could allow a great number of different colors to be generated informing the user of the illuminated button assembly of many different operating conditions. 
       FIG.  31 D  shows how actuation of button  3102  with force  3115  causes a portion of button  3102  to slide into an interior volume defined by housing  3111 . Because illumination elements  3114  are affixed directly to a rear surface of button  3102 , the amount of light projected through illumination window  3104  remains constant regardless of the amount of movement made by button  3102 . This differs from conventional buttons having illumination elements positioned on a printed circuit board that includes an electrical switch. Consequently, in the conventional configuration the amount of illumination increases during button actuation as the button gets closer to the illumination elements during actuation. It should be noted that in the design depicted in  FIGS.  31 C- 31 D , electrical switch  3116  is affixed to a bracket  3118  to keep electrical switch  3116  in a fixed position. In this way, when a rear-facing surface of button  3102  comes in contact with electrical switch  3116 , bracket  3118  provides an amount of resistance sufficient to register the actuation. Electrical switch  3116  can take the form of a dome switch, which is also helpful in providing tactile feedback to a user of illumination button assembly  3100 . 
       FIG.  31 E  shows a perspective view of illuminated window  3104 . Illuminated window  3104  includes securing features  3112  protruding from a tapered body of illuminated window  3104 . It should be appreciated that laterally protruding securing features  3112  can take many forms. At minimum, securing features  3112  are engaged with a laterally oriented notch that prevents dislodgment of illuminated window  3104  from button  3102 . In some embodiments, illuminated window  3104  can insert molded into an opening defined by button  3102 . In this type of insert molding operation, the opening defined by button  3102  could determine the shape and size of illuminated window  3104 . 
     Removable Earpieces 
       FIGS.  32 A- 32 B  show perspective views of a pivot assembly associated with a removable earpiece engaged by a stem base of a headphone band. In particular, pivot assembly  3202  is configured to accommodate rotation of the associated earpiece relative to the headphone band about axes of rotation  3204  and  3206 .  FIG.  32 A  depicts stem base  3208  engaged and locked into place within pivot assembly  3202 . A distal end  3210  of stem base  3208  is locked in place by latch plate  3212 . In particular, latch plate  3212  includes walls that define an aperture  3214  that engages a neck of stem base  3208  to prevent inadvertent removal of stem base  3208  from pivot assembly  3202 .  FIG.  32 A  also shows a portion of earpiece housing  3216  that provides an opening accommodating switch mechanism  3218 . Switch mechanism  3218  is configured to allow stem base  3208  to be released from pivot assembly  3202 . Switch mechanism  3218  includes a protruding engagement member  3220 , which is configured to contact force translation member  3222 . In some embodiments, switch mechanism  3218  can be concealed beneath a removable earpad assembly. 
       FIG.  32 B  shows how a force  3224  exerted upon switch mechanism  3218  is applied to translation member  3222  by engaging member  3220 . The angled end of engagement member  3220  transmits force  3224  to a first post  3226  of force translation member  3222 , which in turn causes force translation member  3222  to rotate about axis of rotation  3228 . Axis of rotation  3228  is defined by a fastener  3227 , which pivotally couples one end of force translation member  3222  to an undepicted portion of earpiece housing  3216 . Rotation of force translation member  3222  about axis of rotation  3228  results in a second post  3230  applying a force  3232  to a wall of latch plate  3212 . Force  3232  applied to latch plate  3212  shifts latch plate  3212  laterally to align aperture  3214  with distal end  3210  of stem base  3208 . Once aperture  3214  is aligned with distal end  3210  of stem base  3208  a force  3234  can be applied to stem base  3208  that allows stem base  3208  to be removed from pivot assembly  3202 . 
       FIGS.  33 A- 33 C  show different views of a latching mechanism  3300  of a pivot assembly.  FIG.  33 A  shows how the pivot assembly includes latch body  3302 , which defines a channel along which latch plate  3304  is configured to slide. Latch body  3302  has a circular geometry that allows it to rotate with a stem base  3306  and its associated stem plug  3308 . Stem plug  3308  includes a contact region  3310 . Contact region  3310  can include multiple electrical contacts for interfacing with circuitry and electrical components disposed within the same earpiece as latching mechanism  3300 . In some embodiments, contact region  3310  includes a number of different electrical contacts, e.g., two, three or four different electrical contacts are possible electrical contact configurations. In some embodiments, both sides of stem plug  3308  can include contact regions that include multiple electrical contacts for interfacing with circuitry and electrical components of an earpiece. It should be noted that latching mechanism  3300  is generally positioned within an earpiece housing so that aperture  3312  is aligned with a stem opening defined by the earpiece housing to allow for insertion of stem base  3306  into both the earpiece housing and aperture  3312  of latching mechanism  3300 . 
       FIG.  33 A  also shows how latch plate  3304  defines an asymmetric aperture  3312 . In  FIG.  33 A , latch plate  3304  is in a latched position where a smaller portion of aperture  3312  is engaged with a narrow neck portion separating stem plug  3308  from the rest of stem base  3306 . By engaging the narrow neck portion with a smaller portion of aperture  3312 , latch plate  3304  can prevent stem base  3306  being removed from latching mechanism  3300 . Latching mechanism also includes latch lever  3314 , which is configured to rotate about axis of rotation  3317 . Torsion spring  3316  is coupled to latch lever  3314  and opposes rotation of latch lever  3314 . A first arm  3318  engages a portion of an earpiece housing (not depicted) and a second arm  3320  engages a portion of latch lever  3314 . When a force  3322  latch lever  3314  is applied to latch lever  3314  it rotates counter-clockwise and exerts a force upon latch plate  3304  sufficient to cause latch plate  3304  to slide laterally within latch body  3302 . When force  3322  is released retaining spring  3324  is configured to exert a force on post  3326  of latch plate  3304  to return latch plate  3304  to the position depicted in  FIG.  33 A . It should be noted that while stem plug  3308  is depicted as being exposed, this is for descriptive purpose only and in some embodiments a plug receptacle configured to mate with stem plug  3308  can be attached to latching mechanism  3300  by one or more of fasteners  3327 . 
       FIGS.  33 B- 33 C  show bottom views of latching mechanism  3300  in locked and unlocked positions. A dotted outline is provided and shows the size and shape of an exemplary pivot mechanism suitable for carrying latching mechanism  3300 .  FIG.  33 B  shows a switch mechanism  3328  that can slide along a channel or groove defined by an associated earpiece housing. Switch mechanism can take the form of a horizontal slider switch that allows for engagement and rotation of latch lever  3314 .  FIG.  33 C  shows how rotation of latch lever  3314  displaces latch plate  3304  laterally such that a larger portion of aperture  3312  is aligned with stem plug  3308 , thereby allowing removal of stem plug  3308  from latching mechanism  3300 .  FIG.  33 C  also shows how retaining spring  3324  is able to deform to accommodate the lateral movement of latch plate  3304  when switch mechanism  3328  is actuated. When pressure is released from switch mechanism  3328 , retaining spring  3324  and torsion spring  3316  cooperatively bias switch mechanism  3328  back to its starting position as depicted in  FIG.  33 B . In some embodiments, it may be desirable to position switch mechanism within a channel of the earpiece housing located such that the switch mechanism is concealed by a removable earpad assembly. For example, in some embodiments, the earpad assembly can be coupled to the earpiece housing by magnets or a series of snaps. 
     Telescoping Stem Mechanism 
       FIG.  34 A  shows headphones  3400  which includes earpieces  3402  and  3404  mechanically coupled together by headband assembly  3406 . Headband assembly includes signal cable  3408 , which electrically couples electrical components within earpieces  3402  and  3404  together. Portions of signal cable  3408  near its opposing ends are arranged in coils  3410 , which are configured to expand and contract to accommodate increases and decreases in the size of headband assembly  3406 . In some embodiments, it can be helpful to include mechanisms that help keep coils  3410  from tangling after undergoing multiple headband assembly telescoping operations. 
       FIG.  34 B  shows a close up view of a stem region  3412  of headband assembly  3406 . In some embodiments, stem region  3412  is made up of multiple different housing components. As depicted, stem region  3412  includes a portion of an upper housing component  3414 , lower housing component  3416  and telescoping component  3418  and stem base  3420 . In some embodiments, telescoping component  3418  and stem base  3420  can be welded together or otherwise permanently coupled together to form a hollow stem defining a channel that accommodates the passage of a coiled portion of cable  3408 . Telescoping component  3418  is shown retracted entirely within an interior volume defined by lower housing component  3416 . In this position, coils  3410  of signal cable  3408  are compressed together to accommodate the shortened length of stem region  3412 . A distal end of telescoping component  3418  includes a funnel element  3422  configured to help guide signal cable  3408  back into the depicted configuration of coils  3410 . Directly behind funnel element  3422  is a first stabilizing element  3424 . First stabilizing element has an outer diameter that is about equal to an inner diameter of lower housing component  3416 . This helps create a slight interference fit between first stabilizing element  3424  and lower housing component  3416  that helps keep the distal end of telescoping component  3418  centered within the interior volume defined by lower housing component  3416 . Directly behind first stabilizing element  3424  is first bearing element  3426 , which has a slightly smaller diameter than first stabilizing element  3424  but is formed of a harder, less resilient material than first stabilizing element  3424 . In this way, first bearing element  3426  can set a hard stop that prevents telescoping component from getting too close to an interior of the interior-facing surface of the walls making up lower housing component  3416 . 
       FIG.  34 B  also shows how a distal end of lower housing component  3416  includes a second bearing element  3428  and a second stabilizing element  3430 . Second stabilizing element has a smaller inner diameter than second bearing element  3428 , allowing second stabilizing element  3430  to help bias telescoping component  3418  toward a central portion of lower housing component  3416  while second bearing element  3428  creates a hard stop that keeps the rest of telescoping component  3418  out of direct contact with other portions of lower housing component  3416 . In this way, both the distal end and proximal ends of telescoping component  3418  are constrained. As telescoping component  3418  telescopes out of lower housing component these constraints help establish a desired amount of friction between the two components and prevent any binding or scraping that could result in undesirable operation or even damage of headband assembly  3406 . It should also be noted that  FIG.  34 B  also depicts stem plug  3308  positioned at a distal end of stem base  3420 . Stem plug  3308  can include two or more electrical contacts for interfacing/electrically coupling with circuitry and electrical components of earpiece  3402  or  3404 . 
       FIG.  34 C  shows a close up view of the distal end of telescoping component  3418 . In particular, funnel element  3422  is depicted having tapered protrusions that extend past the end of telescoping component  3418 . The tapered geometry of the protrusions helps align adjacent coils  3410  as they pass through funnel element  3422  and into telescoping component  3418 . As depicted, some of adjacent coils are misaligned. This misalignment can be corrected at least in part by the tapered geometry of funnel element  3422 . First stabilizing element  3424  is depicted immediately behind funnel element  3422 . First stabilizing element  3424  can include a series of axially aligned ribs that interface with and cause minor amounts of friction with interior-facing surfaces of lower housing component  3416 . In some embodiments, a layer of lubricant can be applied within lower housing component  3416  in order to reduce an amount of resistance generated by friction between the components. It should be noted that a number, thickness and spacing between the axially aligned ridges can be tuned to achieve a desired amount of friction between the components. First stabilizing element  3424  and funnel element  3422  both includes radial stabilization elements  3432  and  3434  that protrude radially from telescoping component  3418  to engage an axially aligned channel defined by interior-facing surfaces of lower housing component  3416 . By engaging this channel, radial stabilization elements  3432  and  3434  are able to prevent unwanted rotation of telescoping component  3418  relative to lower housing component  3416 . 
       FIG.  34 C  also shows first bearing element  3426 , which can also include a radial stabilizing element  3436 . In some embodiments, radial stabilizing element  3436  can also include a spring that helps keep telescoping component  3418  stabilized within lower housing component  3416 . It should be noted that first bearing element has an outer diameter that is slightly smaller than first stabilizing element  3424  and a slightly larger outer diameter than the rest of telescoping component  3418 , which can take the form of a hollow tube formed from aluminum, stainless steel or other robust lightweight materials. 
       FIG.  34 D  shows a cross-sectional view of a distal end of telescoping component  3418  in accordance with section line L-L as depicted in  FIG.  34 B . In particular, lower housing component  3416  is shown defining multiple axially aligned channels configured to accommodate radial stabilization elements  3432 . As depicted, telescoping component also include ridges that support a portion of and provide a robust support for radial stabilization elements  3432 .  FIG.  34 D  also depicts how the ridges of first stabilization element  3424  define multiple channels that reduce the total surface area contact between first stabilization element  3424  and an interior-facing surface of lower housing component  3416 . 
       FIG.  34 E  shows a cross-sectional view of a distal end of lower housing component  3416  in accordance with section line M-M as depicted in  FIG.  34 B . In particular, lower housing component  3416  is shown having a wider diameter at its distal end than the rest of the length of lower housing component  3416 . This wider diameter end of lower housing component  3416  allows for second stabilizing element  3430  to have a greater amount of compliant material positioned between telescoping component  3418  and lower housing component  3416 . This larger amount of material can beneficially provide a greater amount of compliance if desired. By rapidly reducing the cross-sectional area of lower housing component  3416 , the large diameter of second stabilizing element  3430  is prevented from being pushed too far into lower housing component during use or assembly. Furthermore, an amount of friction between second stabilizing element  3430  and telescoping component  3418  can be reduced or tuned by the number and size of the channels  3440  formed by ridges arranged along an inner diameter of stabilizing element  3430 . 
       FIGS.  34 F- 34 H  show a number of alternative embodiments that allow for a larger or smaller amount of play to be established between lower housing component  3416  and telescoping component  3418 . In  FIG.  34 F , wedge-shaped radial stabilization elements can be used to counter play in all degrees of freedom. A small gap can be established between radial stabilization elements  3442  and telescoping component  3418 . The small gap can be used to create extra play in a single direction to add additional play needed to accommodate any differences in the curvature of lower housing component  3416  and telescoping component  3418 . In such a configuration a radial location of radial stabilization elements  3442  and its supporting channels correspond to a direction of curvature of lower housing component  3416  and telescoping component  3418 . The configuration shown in  FIG.  34 G  accommodates a certain amount of rotation of telescoping component  3418  relative to lower housing component  3416  and also accommodates movement in the X-axis. The configuration shown in  FIG.  34 H  shows how telescoping component  3418  can be constrained both radially and in the X-axis direction allowing movement of telescoping component  3418  only in the Y-axis. 
       FIGS.  34 I- 34 J  show telescoping component  3418  disposed within an interior volume defined by lower housing component  3416 . In  FIG.  34 I , lower housing component includes multiple compliant members  3444  arranged at a regular interval along an interior surface of lower housing component  3416 . Compliant members  3444  could take many forms including compliant spring members that while allowing for displacement do not unduly add friction during movement of telescoping component  3418 . In  FIG.  34 J , telescoping component  3418  is shown compressing a stabilization element  3446  until it is stopped when it contacts bearing element  3448  which can be constructed from material that is substantially more rigid than stabilization element  3446 . In some embodiments, stabilization element  3446  can be formed from a material such as an FKM (fluoroelastomers) while bearing element  3448  can be formed from a material such as PEEK (polyether ether ketone). 
     While each of the aforementioned improvements has been discussed in isolation it should be appreciated that any of the aforementioned improvements can be combined. For example, the synchronized telescoping earpieces can be combined with the low spring-rate band embodiments. Similarly, off-center pivoting earpiece designs can be combined with the deformable form-factor headphones designs. In some embodiments, each type of improvement can be combined together to produce headphones with the described advantages from the incorporated types of improvements. 
     The various aspects, embodiments, implementations or features of the described embodiments can be used separately or in any combination. Various aspects of the described embodiments can be implemented by software, hardware or a combination of hardware and software. The described embodiments can also be embodied as computer readable code on a computer readable medium for controlling manufacturing operations or as computer readable code on a computer readable medium for controlling a manufacturing line. The computer readable medium is any data storage device that can store data, which can thereafter be read by a computer system. Examples of the computer readable medium include read-only memory, random-access memory, CD-ROMs, HDDs, DVDs, magnetic tape, and optical data storage devices. The computer readable medium can also be distributed over network-coupled computer systems so that the computer readable code is stored and executed in a distributed fashion. 
     The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the described embodiments. However, it will be apparent to one skilled in the art that the specific details are not required in order to practice the described embodiments. Thus, the foregoing descriptions of specific embodiments are presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the described embodiments to the precise forms disclosed. It will be apparent to one of ordinary skill in the art that many modifications and variations are possible in view of the above teachings. 
     The following paragraphs list numbered claims describing embodiments disclosed herein. 
     1. An earpiece, comprising: a housing defining a cavity for accommodating an ear of a user; an active noise cancelling system; an annular earpad coupled to the housing; and a textile layer wrapped around the annular earpad, the textile layer including a first region and a second region, the first region having a lower porosity than the second region of the textile layer. 
     2. The earpiece as recited in claim  1 , wherein the textile layer is formed from a single layer of material and the porosity of the first region is lowered by applying a heat treatment to the first region. 
     3. The earpiece as recited in claim  1 , wherein the annular earpad has an undercut geometry. 
     4. The earpiece as recited in claim  1 , wherein the annular earpad has an asymmetric geometry that conforms with cranial contours of a head of the user. 
     5. The earpiece as recited in claim  1 , wherein the active noise cancelling system comprises a microphone disposed within the earpiece, and wherein the housing defines an audio entrance opening for the microphone that is laterally offset from the microphone. 
     6. The earpiece as recited in claim  5 , wherein the housing comprises an aluminum housing component that defines the audio entrance opening. 
     7. The earpiece as recited in claim  1 , wherein the cavity has an undercut geometry that is cooperatively defined by the annular earpad and the housing. 
     8. A portable listening device, comprising: an earpiece housing defining a cavity for accommodating an ear of a user; a headband assembly coupled to the earpiece housing; an active noise cancelling system; an earpad assembly coupled to the earpiece housing; and a textile layer wrapped around the earpad assembly, the textile layer including a first region and a second region, the first region having a lower porosity than the second region of the textile layer. 
     9. The portable listening device as recited in claim  8 , wherein the first region has an annular geometry positioned over a portion of the textile layer positioned along a periphery of the earpad assembly to improve passive noise attenuation characteristics of the earpad. 
     10. The portable listening device as recited in claim  8 , wherein the earpad assembly comprises an annular earpad formed by performing a subtractive machining operation on an open cell foam block. 
     11. The portable listening device as recited in claim  10 , wherein the annular earpad has a non-rectangular cross-sectional geometry. 
     12. The portable listening device as recited in claim  10 , wherein the earpad assembly comprises a compliant structural member that couples the annular earpad to the earpiece housing. 
     13. A portable listening device, comprising: a first earpiece; a second earpiece; a headband assembly coupling the first earpiece to the second earpiece; a magnetic field sensor assembly disposed within the first earpiece and configured to measure an amount of rotation of the first earpiece relative to the headband assembly; and a processor configured to change an operating state of the portable listening device based on the amount of rotation measured by the magnetic field sensor assembly. 
     14. The portable listening device as recited in claim  13 , wherein at least a portion of the magnetic field sensor assembly is coupled to a portion of a stem of the headband assembly and disposed within the first earpiece. 
     15. The portable listening device as recited in claim  13 , wherein the processor is configured to change the operating state when the measured amount of rotation exceeds a predetermined threshold. 
     16. The portable listening device as recited in claim  14 , wherein the magnetic field sensor assembly comprises: first and second permanent magnets coupled to the portion of the stem; and a magnetic field sensor coupled to a housing of the first earpiece. 
     17. The portable listening device as recited in claim  14 , wherein the magnetic field sensor assembly comprises: a magnetic field sensor coupled to the portion of the stem; and first and second permanent magnets coupled to a housing of the first earpiece. 
     18. The portable listening device as recited in claim  16 , wherein a polarity of a first magnetic field emitted by the first permanent magnet is oriented in a first direction and a polarity of a second magnetic field emitted by the second permanent magnet is oriented in a second direction opposite the first direction. 
     19. The portable listening device as recited in claim  13 , wherein the processor is configured to control the operating state based on the amount of rotation measured by the magnetic field sensor assembly, the magnetic field sensor assembly being configured to identify three or more different locations of the headband assembly relative to the first earpiece. 
     20. The portable listening device as recited in claim  15 , wherein the headphones enter a low power state when the amount of rotation detected by the magnetic field sensors assembly is below the predetermined threshold. 
     21. The portable listening device as recited in claim  13 , further comprising an optical sensor assembly disposed within the first earpiece and configured to direct light waves at an ear of a user, wherein the processor is configured to confirm the change in operating state based on output from the optical sensor assembly. 
     22. The portable listening device as recited in claim  13 , wherein the portable listening device comprises headphones. 
     23. A carrying case, comprising: a case housing defining first and second earpiece recesses configured to receive first and second earpieces of corresponding headphones; and a permanent magnet positioned adjacent to a portion of the first earpiece recess corresponding to the first earpiece of the corresponding headphones, the permanent magnet being positioned to emit a magnetic field that interacts with a sensor within the first earpiece of the headphones. 
     24. The carrying case as recited in claim  23 , wherein the magnetic field emitted by the permanent magnet includes one or more characteristics detectable by the sensor within the first earpiece. 
     25. The carrying case as recited in claim  23 , wherein the first and second earpiece recesses are configured to receive respective first and second earcups of the corresponding headphones. 
     26. A system, comprising: a carrying case, comprising: a case housing defining first and second earcup recesses configured to receive first and second earcups of corresponding headphones, the carrying case comprising a permanent magnet positioned proximate a periphery of the first earcup recess; and headphones, comprising: first and second earpieces; a headband assembly coupling the first and second earpieces together; a magnetic field sensor positioned along a periphery of the first earpiece; and a processor configured to change an operating state of the headphones in response to detecting a magnetic field emitted by the permanent magnet. 
     27. The system as recited in claim  26 , wherein the headphones further comprise an ambient light sensor, wherein the processor is configured to change the operating state of the headphones to a low power state in response to detecting the magnetic field and receiving low light readings from the ambient light sensor. 
     28. An earpiece, comprising: an earpiece housing comprising a back wall and side walls that cooperatively define an interior volume; a speaker assembly disposed within the interior volume, the speaker assembly comprising: a permanent magnet defining a channel extending therethrough; a diaphragm; an electrically conductive coil coupled to the diaphragm and configured to generate a first magnetic field that interacts with a second magnetic field emitted by the permanent magnet to induce oscillation of the diaphragm; and a speaker frame member extending across a portion of the back wall of the earpiece housing to further define a rear volume of air that extends through the channel. 
     29. The earpiece as recited in claim  28 , wherein the speaker frame member defines the rear volume such that it extends to a peripheral portion of the earpiece housing that defines an air vent. 
     30. The earpiece as recited in claim  28 , wherein the portion of the back wall is a majority of the back wall. 
     31. The earpiece as recited in claim  28 , wherein an average distance between the speaker frame member and the back wall of the earpiece housing is about 1 mm. 
     32. The earpiece as recited in claim  28 , wherein portions of the speaker frame member are glued to the back wall of the earpiece housing and wherein the rear volume is routed around the portions of the speaker frame member glued to the back wall. 
     33. The earpiece as recited in claim  28 , wherein the permanent magnet is a first permanent magnet and the earpiece further comprises a second permanent magnet surrounding the first permanent magnet and cooperatively forming a channel shaped to accommodate the electrically conductive coil. 
     34. A portable listening device, comprising: a headband assembly; an earpiece housing defining an interior volume, the earpiece housing being coupled to the headband assembly; a speaker assembly disposed within the interior volume, the speaker assembly comprising: a diaphragm; a permanent magnet defining a channel extending therethrough that connects a rear volume of air disposed directly behind the diaphragm to another volume of air extending radially outward from the diaphragm; and an electrically conductive coil coupled to the diaphragm and configured to generate a first magnetic field that interacts with a second magnetic field emitted by the permanent magnet to induce oscillation of the diaphragm. 
     35. The portable listening device as recited in claim  34 , wherein the other volume of air extends across a majority of a rear wall of the earpiece housing. 
     36. The portable listening device as recited in claim  34 , further comprising a speaker frame member that defines the other volume of air extending radially outward from the diaphragm. 
     37. An earpiece, comprising: a housing defining a cavity configured to accommodate an ear of a user; a speaker disposed within the housing; a first battery disposed within the housing; and a second battery disposed within the housing, the cavity being positioned between the first and second batteries. 
     38. The earpiece as recited in claim  37 , wherein the first and second batteries are tilted diagonally away from the cavity. 
     39. The earpiece as recited in claim  37 , further comprising third and fourth batteries disposed within the housing. 
     40. The earpiece as recited in claim  39 , wherein the first, second, third and fourth batteries are each discrete battery assemblies. 
     41. The system as recited in claim  26 , wherein the carrying case further comprises a second permanent magnet positioned proximate a periphery of the second earcup recess.

Metadata:
Filing Date: 20230515
Publication Date: 20240514
Grant Date: 20240514
Priority Date: 20171120
Inventors: SIAHAAN, EDWARD
BLOOM, DANIEL R.
LEBLANC, JASON J.
QIAN, Phillip
Assignee: APPLE INC
CPC Classifications: [{"code": "H04R1/1008", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R1/1008", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04R1/1033", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R1/1041", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R1/105", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R1/1066", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R1/1075", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R1/1083", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R5/0335", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R5/04", "inventive": true, "first": false, "tree": "[]"}, {"code": "G10K11/17861", "inventive": false, "first": false, "tree": "[]"}, {"code": "G10K11/17873", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R1/1033", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04R5/0335", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04R5/0335", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04R1/1008", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04R1/1066", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R1/1058", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R5/0335", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R1/1033", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R1/1058", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R1/1066", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R1/1041", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R1/1033", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R1/1066", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R1/1066", "inventive": true, "first": false, "tree": "[]"}, {"code": "G10K11/17861", "inventive": false, "first": false, "tree": "[]"}, {"code": "G10K11/17873", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R1/1083", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R5/0335", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R1/1033", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R1/1041", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R1/105", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R1/1075", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R5/04", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 64650575