PATENT DOCUMENT

Publication Number: US-12063466-B2
Application Number: US-202217895028-A
Country: US
Kind Code: B2

Title: Charging case for portable wireless listening device

Abstract:
A charging case for a pair of wireless earphones comprising: a housing having a peripheral wall that defines a shell; a frame insert coupled to the housing and extending into the shell, the frame insert having one or more insert walls that define first and second pockets sized and shaped to accept first and second wireless earphones, respectively, wherein the one or more insert walls cooperate with the housing primary wall to define a sealed chamber within the charging case; a lid coupled to the housing and operable between a closed position in which the lid covers the first and second pockets and an open position in which the first and second pockets are exposed; a speaker module disposed within the sealed chamber, the speaker module comprising an audio driver having a diaphragm that separates a front volume of the audio driver from a back volume of the audio driver and a speaker vent disposed within the back volume; one or more first openings formed through the peripheral wall and opening into the front volume, wherein the audio driver is positioned and aligned to emit sound into the front volume and through the one or more acoustic openings; and one or more second openings formed through the peripheral wall at a location spaced apart from the front volume, wherein at least one of the one or more second openings is an acoustic vent acoustically coupled to the back volume of the audio driver through the speaker vent ear tip.

Claims:
What is claimed is: 
     
       1. A charging case for a pair of wireless earphones, the charging case comprising:
 a housing having a peripheral wall that defines a shell; 
 a frame insert coupled to the housing and extending into the shell, the frame insert having one or more insert walls that define first and second pockets sized and shaped to accept first and second wireless earphones, respectively, wherein the one or more insert walls cooperate with the housing primary wall to define a sealed chamber within the charging case; 
 a lid coupled to the housing and operable between a closed position in which the lid covers the first and second pockets and an open position in which the first and second pockets are exposed; 
 a speaker module disposed within the sealed chamber, the speaker module comprising an audio driver having a diaphragm that separates a front volume of the audio driver from a back volume of the audio driver and a speaker vent disposed within the back volume; 
 one or more first openings formed through the peripheral wall and opening into the front volume, wherein the audio driver is positioned and aligned to emit sound into the front volume and through the one or more acoustic openings; and 
 one or more second openings formed through the peripheral wall at a location spaced apart from the front volume, wherein at least one of the one or more second openings is an acoustic vent acoustically coupled to the back volume of the audio driver through the speaker vent. 
 
     
     
       2. The charging case set forth in  claim 1  further comprising a multi-layer mesh spanning across the acoustic vent, the multi-layer mesh comprising an outer cosmetic mesh, an inner clad layer comprising a non-woven thermoplastic layer and a hydrophobic layer, and an acoustic mesh disposed between the cosmetic mesh and the clad layer. 
     
     
       3. The charging case set forth in  claim 2  wherein the inner clad layer comprises a clad between a non-woven polyethylene terephthalate (PET) mesh layer and a hydrophobic Polytetrafluoroethylene (PTFE) layer. 
     
     
       4. The charging case set forth in  claim 2  wherein the cosmetic mesh includes, for each of the one or more second openings, a protrusion that extends from within the housing into the respective second opening. 
     
     
       5. The charging case set forth in  claim 1  further comprising a cosmetic mesh spanning the one or more first openings and a water proof membrane coupled to an interior surface of the cosmetic mesh. 
     
     
       6. The charging case set forth in  claim 4  wherein the cosmetic mesh includes, for each of the one or more first openings, a protrusion that extends from within the housing into the respective first opening. 
     
     
       7. The charging case set forth in  claim 1  further comprising an eyelet mechanically attached to a peripheral wall of the charging case. 
     
     
       8. The charging case set forth in  claim 1  wherein each of the first and second pockets of the frame insert include a generally tubular portion that extends from an upper portion of the housing towards a bottom surface of the peripheral wall and wherein the charging case further comprises a wireless antenna that extends from a bottom portion of the housing towards an upper portion of the housing in an area between one of the first and second pockets and a side surface of the peripheral wall. 
     
     
       9. The charging case set forth in  claim 1  wherein the sealed chamber is sealed in accordance within at least IPX4 requirements. 
     
     
       10. The charging case set forth in  claim 1  wherein the charging case is less than 2½ inches long, less than 2 inches high and less than 1 inch deep. 
     
     
       11. The charging case set forth in  claim 1  further comprising controller circuitry including a processor and memory, wherein the memory includes computer-readable instructions that when executed by the processor communicate with a host device to respond to commands to emit sound over the speaker. 
     
     
       12. The charging case set forth in  claim 1  further comprising circuitry and an antenna that cooperate to wirelessly send a secure signal including information indicating a physical location of the charging case that can be detected by external devices over a wireless network. 
     
     
       13. A charging case for a pair of wireless earphones, the charging case comprising:
 a housing having a peripheral wall that defines a shell; 
 a frame insert coupled to the housing and extending into the shell, the frame insert having one or more insert walls that define first and second pockets sized and shaped to accept first and second wireless earphones, respectively, wherein the one or more insert walls cooperate with the housing primary wall to define a sealed chamber within the charging case; 
 a lid coupled to the housing and operable between a closed position in which the lid covers the first and second pockets and an open position in which the first and second pockets are exposed; 
 a speaker module disposed within the sealed chamber, the speaker module comprising an audio driver having a diaphragm that separates a front volume of the audio driver from a back volume of the audio driver and a speaker vent disposed within the back volume; 
 one or more first openings formed through the peripheral wall and opening into the front volume, wherein the audio driver is positioned and aligned to emit sound into the front volume and through the one or more acoustic openings; 
 one or more second openings formed through the peripheral wall at a location spaced apart from the front volume, wherein at least one of the one or more second openings is an acoustic vent acoustically coupled to the back volume of the audio driver through the speaker vent; and 
 controller circuitry including a processor and memory, wherein the memory includes computer-readable instructions that when executed by the processor communicate with a host device to respond to commands to emit sound over the speaker. 
 
     
     
       14. The charging case set forth in  claim 13  further comprising a multi-layer mesh spanning across the acoustic vent, the multi-layer mesh comprising an outer cosmetic mesh, an inner clad layer comprising a non-woven thermoplastic layer and a hydrophobic layer, and an acoustic mesh disposed between the cosmetic mesh and the clad layer. 
     
     
       15. The charging case set forth in  claim 14  wherein the inner clad layer comprises a clad between a non-woven polyethylene terephthalate (PET) mesh layer and a hydrophobic Polytetrafluoroethylene (PTFE) layer. 
     
     
       16. The charging case set forth in  claim 14  wherein the cosmetic mesh includes, for each of the one or more second openings, a protrusion that extends from within the housing into the respective second opening. 
     
     
       17. The charging case set forth in  claim 13  further comprising a cosmetic mesh spanning the one or more first openings and a water proof membrane coupled to an interior surface of the cosmetic mesh. 
     
     
       18. The charging case set forth in  claim 13  wherein each of the first and second pockets of the frame insert include a generally tubular portion that extends from an upper portion of the housing towards a bottom surface of the peripheral wall and wherein the charging case further comprises a wireless antenna that extends from a bottom portion of the housing towards an upper portion of the housing in an area between one of the first and second pockets and a side surface of the peripheral wall. 
     
     
       19. The charging case set forth in  claim 13  wherein the charging case is less than 2½ inches long, less than 2 inches high and less than 1 inch deep. 
     
     
       20. The charging case set forth in  claim 13  further comprising an eyelet mechanically attached to a peripheral wall of the charging case.

Description:
This application claims priority to U.S. Provisional Patent Application No. 63/268,356 filed on Feb. 22, 2022, which is incorporated herein by reference in its entirety for all purposes. 
    
    
     BACKGROUND 
     Portable listening devices, such as headphones, can be used with a wide variety of electronic devices such as portable media players, smart phones, tablet computers, laptop computers, stereo systems, and other types of devices. Portable listening devices have historically included one or more small speakers configured to be place on, in, or near a user&#39;s ear, structural components that hold the speakers in place, and a cable that electrically connects the portable listening device to an audio source. Wireless portable listening devices that do not include a cable and instead, wirelessly receive a stream of audio data from a wireless audio source, have become ubiquitous over the last several years. Such wireless portable listening devices can include, for instance, wireless earbud devices or wireless in-ear hearing devices that operate in pairs (one for each ear) or individually for outputting sound to, and receiving sound from, the user. 
     While wireless portable listening devices have many advantages over wired portable listening devices and have become a very popular with consumers, improved wireless portable listening devices are desirable. 
     BRIEF SUMMARY 
     The present disclosure describes various embodiments of portable listening devices that can enable a user to experience high-end acoustic performance and a pleasant, positive user experience as well as various embodiments of deformable ear tips that can improve the listening experience. Other embodiments pertain to a case for charging and storing one or more portable wireless listening devices. Still other embodiments pertain to a system that includes both a pair of portable wireless listening devices and a charging case for the devices. 
     According to some embodiments, an earphone is provided. The earphone can include: a device housing that defines an interior cavity within the device housing; an acoustic port formed through a wall of the device housing; an audio driver disposed within the device housing and aligned to emit sound through the acoustic port; a user input region disposed along an exterior surface of the device housing; a flex circuit disposed within the interior cavity, the flex circuit including a first portion bonded at a first location to an inner surface of the device housing directly beneath the user-input region, a second portion bonded at a second location to an inner surface of the device housing spaced apart from the first location, and a third portion extending between the first and second portions; a force pixel disposed within the interior cavity and mounted to the first portion of the flex circuit below the user input region; a plurality of touch pixels disposed within the interior cavity between the force pixel and the user input region; sensor control circuitry disposed within the interior cavity and mounted to the second portion of the flex circuit; and a wireless antenna disposed within the interior cavity defined by the device housing. 
     In some embodiments an earphone can include: a device housing including a speaker housing and a stem extending away from the speaker housing portion, wherein the speaker housing and stem combine to define an interior cavity within the device housing; an acoustic port formed through a wall of the speaker housing; an audio driver disposed within the speaker housing and aligned to emit sound through the acoustic port; a user input region disposed along an exterior surface of the stem; a flex circuit disposed within the interior cavity, the flex circuit including a first portion bonded at a first location to an inner surface of the stem directly beneath the user-input region, a second portion bonded at a second location to an inner surface of the stem spaced apart from the first location, and a third portion extending between the first and second portions; a force pixel disposed within the interior cavity and mounted to the first portion of the flex circuit below the user input region; a plurality of touch pixels disposed within the interior cavity between the force pixel and the user input region; sensor control circuitry disposed within the interior cavity and mounted to the second portion of the flex circuit; and an antenna disposed within the interior cavity along a length of the stem. 
     In various implementations, the earphone can include one or more of the following features. The touch pixels can be formed within the first portion of the flex circuit. The force pixel can include a first capacitive plate mounted to the flex circuit and a second capacitive plate mounted to the antenna in a spaced apart relationship with the first capacitor plate. The force pixel further can include a foam layer coupled between the first and second capacitor plates. The plurality of touch pixels can be spaced apart from each other along a length of the stem within the user input region. The flex circuit can be laminated to the inner surface of the housing at the first and second locations using a b-stage system in which a first low temperature cure step partially cures the adhesive material and is followed by a UV cure step to fully cure the adhesive and bond the laminate to the wall. The sensor control circuitry can be operatively coupled to excite and capture signals from both the touch pixels and the force pixel. The sensor control circuitry can include an application specific integrated circuit (ASIC) that is operatively coupled to excite the touch pixels and the force pixel at a common frequency. 
     In various implementations, the sensor control circuitry can include one or more of the following features. The sensor control circuitry can be responsive to at least first, second and third operating modes that differ from each other in an amount of power consumed by the sensor control circuitry and force and touch sensors. The first operating mode can be activated upon receiving one or more signals indicating that the earphones are not within a charging case and not within an ear of a user. The second operating mode can be activated upon a receiving one or more signals that the earphones are detected within an ear of a user while not being actively used. The third operating mode can be activated upon a receiving one or more signals that the earphones are detected within an ear of a user while being actively used. When in the first operating mode, the sensor control circuitry can electrically couple the plurality of touch pixels together and sample the plurality of touch pixels together as a single touch pixel. When in the third operating mode, the sensor control circuitry can monitor each of the plurality of touch pixels separately. When in the first operating mode, the sensor control circuitry can sample the force pixel and the plurality of touch pixels at a baseline frequency rate. When in the third operating mode, the sensor control circuitry can sample the force pixel and the plurality of touch pixels at a standard frequency that is substantially higher than the baseline frequency rate. When in the second operating mode, the sensor control circuitry can electrically couple the plurality of touch pixels together and sample the plurality of touch pixels together as a single touch pixel and force pixel at the standard frequency rate. The sensor control circuitry can be further responsive to fourth and fifth operating modes where, in each of the fourth and fifth operating modes the sensor control circuitry and force and touch sensors consume less power than in any of the first, second and third operating modes. The fourth operating mode can be activated upon receiving one or more signals that indicate the earphone is in the charging case and fully charged. The fifth operating mode can be activated upon receiving one or more signals that indicate the earphone is in the charging case and either not fully charged or that a lid of the charging case is open. When in the third operating mode, the sensor control circuitry can repeatedly perform a plurality of sensor status checks at a standard frequency rate. In each sensor status check, the sensor control circuitry can perform a plurality of operations including: detecting a noise level, detecting whether the force sensor has been activated, and individually detecting whether each of the plurality of touch pixels has been activated. The sensor control circuitry can execute a baseline procedure check at a baseline frequency rate that is at least an order of magnitude less than the standard frequency rate. During each baseline procedure check, the sensor control circuitry can perform a first plurality of operations in which a voltage signal is applied to the force and touch pixels at a first frequency and then perform a second plurality of operations in which the voltage signal is applied to the force and touch pixels at a second frequency, different from the first frequency. The plurality of first and second operations can each include: detecting a noise level, detecting whether the force sensor has been activated, and individually detecting whether each of the plurality of touch pixels has been activated. 
     According to some embodiments, a deformable ear tip is provided. The ear tip can include: an annular inner ear tip body having a sidewall extending between first and second opposing ends thereby defining a sound channel through the ear tip; an annular outer flange integrally formed with and surrounding the first end of the inner ear tip body and extending towards the inner ear tip second end forming an air gap between the annular inner ear tip body and the annular outer flange along a portion of a length of the ear tip, wherein the outer flange comprises a first material having a first durometer and is sized and shaped to be inserted into a human ear canal; and an inner flange integrally formed with the inner ear tip body and comprising a second material having a second durometer less than the first durometer, the inner flange body extending from a location along the inner ear tip body between the first and second ends towards an inner surface of the outer flange body. 
     In various implementations, the ear tip can include one or more of the following features. The outer flange can have a first radius of curvature and the inner flange can have a second radius of curvature greater than the first radius of curvature. The ear tip can be formed with a double shot injection molding process in which one shot forms the outer flange and an upper portion of the inner ear tip body and a second shot forms the inner flange and a lower portion of the inner ear tip body. The inner flange can extend fully around a perimeter of the inner ear tip body. The inner flange can physical contacts the inner surface of the outer flange. The inner flange can physically contact the inner surface of the outer flange at a location where the outer flange curves inward towards the inner ear tip body. The sidewall of the inner ear tip body can gradually vary in thickness from a first thickness at the first end to a second thickness at the second end. The second thickness can be greater than the first thickness. The ear tip can further include an annular rigid attachment structure coupled to the second end of the inner ear tip body. The annular rigid attachment member can include an attachment member sidewall that defines a central opening that is aligned with and forms part of the sound channel. The attachment member sidewall can include at least one control leak formed there through creating an acoustic pathway between an ambient environment and the sound channel. 
     According to some embodiments, an earphone charging case is provided. The charging case can include: a housing having a peripheral wall that defines a shell; a frame insert coupled to the housing and extending into the shell, the frame insert having one or more insert walls that define first and second pockets sized and shaped to accept first and second wireless earphones, respectively, wherein the one or more insert walls cooperate with the housing primary wall to define a sealed chamber within the charging case; a lid coupled to the housing and operable between a closed position in which the lid covers the first and second pockets and an open position in which the first and second pockets are exposed; a speaker module disposed within the sealed chamber, the speaker module comprising an audio driver having a diaphragm that separates a front volume of the audio driver from a back volume of the audio driver and a speaker vent disposed within the back volume; one or more first openings formed through the peripheral wall and opening into the front volume, wherein the audio driver is positioned and aligned to emit sound into the front volume and through the one or more acoustic openings; and one or more second openings formed through the peripheral wall at a location spaced apart from the front volume, wherein at least one of the one or more second openings is an acoustic vent acoustically coupled to the back volume of the audio driver through the speaker vent. 
     In various implementations, an earphone charging case can include one or more of the following features. The charging case can include a multi-layer mesh spanning across the acoustic vent. The multi-layer mesh can include an outer cosmetic mesh, an inner clad layer, and an acoustic mesh disposed between the cosmetic mesh and the clad layer. The inner clad layer can include a non-woven thermoplastic layer and a hydrophobic layer, and in some implementations the inner clad layer can include a non-woven polyethylene terephthalate (PET) mesh layer and a hydrophobic Polytetrafluoroethylene (PTFE) layer. The cosmetic mesh can include, for each of the one or more second openings, a protrusion that extends from within the housing into the respective second opening. The charging case can include an eyelet mechanically attached to a peripheral wall of the charging case. Each of the first and second pockets of the frame insert can include a generally tubular portion that extends from an upper portion of the housing towards a bottom surface of the peripheral wall. The charging case can include a wireless antenna that extends from a bottom portion of the housing towards an upper portion of the housing in an area between one of the first and second pockets and a side surface of the peripheral wall. The sealed chamber can be sealed in accordance within at least IPX4 requirements. The charging case can be less than 2½ inches long, less than 2 inches high and less than 1 inch deep. The charging case can include controller circuitry including a processor and memory, wherein the memory includes computer-readable instructions that, when executed by the processor, communicate with a host device to respond to commands to emit sound over the speaker. The charging case can include circuitry and an antenna that cooperate to wirelessly send a secure signal including information indicating a physical location of the charging case that can be detected by external devices over a wireless network. 
     To better understand the nature and advantages of the present invention, reference should be made to the following description and the accompanying figures. It is to be understood, however, that each of the figures is provided for the purpose of illustration only and is not intended as a definition of the limits of the scope of the present invention. Also, as a general rule, and unless it is evident to the contrary from the description, where elements in different figures use identical reference numbers, the elements are generally either identical or at least similar in function or purpose. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a simplified illustration of an exemplary portable electronic listening device system having a host device configured as a smart phone, a case, and a pair of wireless listening devices configured as earbuds, according to some embodiments; 
         FIG.  2    is a simplified block diagram of various components of a portable wireless listening system according to some embodiments; 
         FIGS.  3 A- 3 C  are simplified views of a portable wireless earbud according to some embodiments; 
         FIG.  4    is a simplified cross-sectional schematic diagram of a previously known in-ear earphone; 
         FIG.  5    is a simplified cross-sectional schematic diagram of an in-ear earphone according to some embodiments; 
         FIGS.  6 A and  6 B  are simplified top plan and cross-sectional views of a nozzle portion of earphone according to some embodiments; 
         FIG.  7    is a simplified cross-sectional view of a portion of an earphone according to some embodiments; 
         FIG.  8    is a simplified cross-sectional view of a portion of an earphone according to some embodiments; 
         FIGS.  9 A and  9 B  are simplified cross-sectional and exploded perspective views, respectively, of a multi-layer mesh according to some embodiments; 
         FIG.  10 A  is a simplified rear perspective view of an earphone having a touch-sensitive and pressure-sensitive user interface according to some embodiments; 
         FIGS.  10 B and  10 C  are simplified cross-sectional illustrations along a width of the stem portion of the earphone depicted in  FIG.  10 A  according to some embodiments; 
         FIGS.  11 A and  11 B  are simplified cross-sectional illustrations along a length of the stem portion of an earphone according to some embodiments; 
         FIG.  11 C  is a simplified cross-sectional illustration along a diameter of the stem portion of an earphone in accordance with some embodiments; 
         FIG.  12    is a state diagram depicting the different power modes according to some embodiments; 
         FIG.  13    is a simplified timing chart depicting sequences of steps associated different states of operation of an earphone according to some embodiments; 
         FIG.  14    is a simplified cross-sectional illustration of a previously known ear tip; 
         FIG.  15    is a simplified cross-sectional illustration of a double flange ear tip according to some embodiments; 
         FIG.  16    is a simplified cross-sectional illustration of a double flange ear tip according to some embodiments; 
         FIG.  17 A  is a simplified illustration of an earphone charging case according to some embodiments in which a lid of the charging case is open; 
         FIGS.  17 B and  17 C  are simplified front view and rear view illustrations, respectively, of the earphone charging case shown in  FIG.  17 A  with the lid of the charging case closed; 
         FIG.  18    is a simplified cross-sectional illustration of an earphone charging case according to some embodiments; 
         FIG.  19 A  is a simplified cross-sectional illustration of a speaker module disposed within an earphone charging case according to some embodiments; 
         FIG.  19 B  is a simplified cross-sectional illustration of a B-vent disposed within an earphone charging case according to some embodiments; and 
         FIG.  20    is a simplified perspective view of a charging case that can store a pair of earbuds according to some embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     Some embodiments of the disclosure pertain to a portable wireless listening that can deliver high-end acoustic performance to a user along with a pleasant and intuitive user experience. Other embodiments pertain to a case for charging and storing one or more portable wireless listening devices. Still other embodiments pertain to a system that includes both a pair of portable wireless listening devices and a charging case for the devices. 
     As used herein, the term “portable listening device” includes any portable device configured to be worn by a user and placed such that a speaker of the portable listening device is adjacent to or in a user&#39;s ear. A “portable wireless listening device” is a portable listening device that is able to receive and/or send streams of audio data from or to a second device without a wire connecting the portable wireless listening device to the second device using, for example, a wireless communication protocol. 
     Headphones are one type of portable listening device, headsets (a combination of a headphone and an attached microphone) are another and hearing aids (in-ear devices that are designed to augment sounds from the surrounding environment to improve a user&#39;s hearing) are still an additional type of portable listening device. As used herein, the term “headphones” represents a pair of small, portable listening devices that are designed to be worn on or around a user&#39;s head. They convert an electrical signal to a corresponding sound that can be heard by the user. Headphones, which can include a microphone incorporated within a housing component of the headphone, include traditional headphones that are worn over a user&#39;s head and include left and right earcups connected to each other by a headband, and earphones (very small headphones that are designed to be fitted directly in a user&#39;s ear). Traditional headphones include both over-ear headphones (sometimes referred to as either circumaural or full-size headphones) that have earpads that fully encompass a user&#39;s ears, and on-ear headphones (sometimes referred to as supra-aural headphones) that have earpads that press against a user&#39;s ear instead of surrounding the ear. 
     The term “earphones”, which can also be referred to as ear-fitting headphones, includes both small headphones, sometimes referred to as “earbuds”, that fit within a user&#39;s outer ear facing the ear canal without being inserted into the ear canal, and in-ear headphones, sometimes referred to as canal phones, that are inserted in the ear canal itself. Thus, earphones can be another type of portable listening device that are configured to be positioned substantially within a user&#39;s ear. As used herein, the term “ear tip”, which can also be referred to as earmold, includes pre-formed, post-formed, or custom-molded sound-directing structures that at least partially fit within an ear canal. Ear tips can be formed to have a comfortable fit capable of being worn for long periods of time. They can have different sizes and shapes to achieve a better seal with a user&#39;s ear canal and/or ear cavity. 
     Example Wireless Listening System 
       FIG.  1    is an example of a wireless listening system  100  according to some embodiments. System  100  can include a host device  110 , a pair of portable wireless listening devices  130  (e.g., left and right earphones) and a charging case  150 . Host device  110  is depicted in  FIG.  1    as a smart phone but can be any electronic device that can transmit audio data to portable listening device  130 . Other, non-limiting examples of suitable host devices  110  include a laptop computer, a desktop computer, a tablet computer, a smart watch, an audio system, a video player, and the like. 
     As depicted graphically in  FIG.  1   , host device  110  can be wirelessly communicatively coupled with portable wireless listening devices  130  and charging case  150  through wireless communication links  160  and  162 . Similarly, portable wireless listening devices  130  can be communicatively coupled to charging case  150  via wireless communication link  164 . Each of the wireless communication links  160 ,  162  and  164  can be a known and established wireless communication protocol, such as a Bluetooth protocol, a WiFi protocol, or any other acceptable protocol that enables electronic devices to wirelessly communicate with each other. Thus, host device  110  can exchange data directly with portable wireless listening devices  130 , such as audio data, that can be transmitted over wireless link  160  to wireless listening devices  130  for play back to a user, and audio data that can be received by host device  110  as recorded/inputted from microphones in the portable wireless listening devices  130 . Host device  110  can also be wirelessly communicatively coupled with charging case  150  via wireless link  162  so that the host device  110  can exchange data with the charging case, such as data indicating the battery charge level data for case  150 , data indicating the battery charge level for portable wireless listening devices  130 , data indicating the pairing status of portable wireless listening devices  130 . 
     Portable wireless listening devices  130  can be stored within case  150 , which can protect the devices  130  from being lost and/or damaged when they are not in use and can also provide power to recharge the batteries of portable wireless listening devices  230  as discussed below. In some embodiments portable wireless listening devices  130  can also be wirelessly communicatively coupled with charging case  150  via wireless link  164  so that, when the devices are worn by a user, audio data from case  150  can be transmitted to portable wireless listening devices  130 . As an example, charging case  150  can be coupled to an audio source different than host device  110  via a physical connection, e.g., an auxiliary cable connection. The audio data from the audio source can be received by charging case  150 , which can then wirelessly transmit the data to wireless listening devices  130 . That way, a user can hear audio stored on or generated by an audio source by way of wireless listening devices  130  even though the audio source does not have wireless audio output capabilities. 
     As will be appreciated herein, portable wireless listening devices  130  can include several features can enable the devices to be comfortably worn by a user for extended periods of time and even all day. Each portable wireless listening device  130  can be shaped and sized to fit securely between the tragus and anti-tragus of a user&#39;s ear so that the portable listening device is not prone to falling out of the ear even when a user is exercising or otherwise actively moving. Its functionality can also enable the wireless listening devices  130  to provide a user interface to host device  110  so that the user may not need to utilize a graphical interface of host device  110  for certain functions or operations of either the portable wireless listening devices or the host device. In other words, wireless listening devices  130  can be sufficiently sophisticated that they can enable the user to perform certain day-to-day operations from host device  110  solely through interactions with wireless listening devices  130 . This can create further independence from host device  110  by not requiring the user to physically interact with, and/or look at the display screen of, host device  110 , especially when the functionality of wireless listening devices  130  is combined with the voice control capabilities of host device  110 . Thus, in some instances portable wireless listening devices  130  can enable a true hands free experience for the user. 
     Details of an example earphone, which can be representative of each of the portable wireless listening devices  130  are discussed below. First, however, reference is made to  FIG.  2   , which is a simplified block diagram of various components of a wireless listening system  200  according to some embodiments that includes a host device  210 , a pair of portable wireless listening devices (PWLDs)  230  (e.g., a right PWLD  230  and a left PWLD  230 ) and a charging case  250 . System  200  can be representative of system  100  shown in  FIG.  1    and host device  210 , portable wireless listening devices  230  and charging case  250  can be representative of host device  110 , portable wireless listening devices  130  and charging case  150 , respectively. Each portable wireless listening device  230  can receive and generate sound to provide an enhanced user interface for host device  210 . For convenience, the discussion below refers to a single portable wireless listening device  230 , but it is to be understood that, in some embodiments, a pair of portable listening devices can cooperate together for use in a user&#39;s left and right ears, respectively, and each portable wireless listening device in the pair can include the same or similar components. 
     Portable wireless listening device  230  can include a computing system  231  that executes computer-readable instructions stored in a memory bank (not shown) for performing a plurality of functions for portable wireless listening device  230 . Computing system  231  can be one or more suitable computing devices, such as microprocessors, computer processing units (CPUs), digital signal processing units (DSPs), field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs) and the like. 
     Computing system  231  can be operatively coupled to a user interface system  232 , communication system  234 , and a sensor system  236  for enabling portable wireless listening device  230  to perform one or more functions. For instance, user interface system  232  can include a driver (e.g., speaker) for outputting sound to a user, one or more microphones for inputting sound from the environment or the user, one or more LEDs for providing visual notifications to a user, a pressure sensor or a touch sensor (e.g., a resistive or capacitive touch sensor) for receiving user input, and/or any other suitable input or output device. Communication system  234  can include wireless and wired communication components for enabling portable wireless listening device  230  to send and receive data/commands from host device  210 . For example, in some embodiments communication system  234  can include circuitry that enables portable wireless listening device  230  to communicate with host device  210  over wireless link  260  via a Bluetooth or other wireless communication protocol. In some embodiments communication system  234  can also enable portable wireless listening device  230  to wirelessly communicate with charging case  250  via wireless link  264 . Sensor system  236  can include proximity sensors (e.g., optical sensors, capacitive sensors, radar, etc.), accelerometers, microphones, and any other type of sensor that can measure a parameter of an external entity and/or environment. 
     Portable wireless listening device  230  can also include a battery  238 , which can be any suitable energy storage device, such as a lithium ion battery, capable of storing energy and discharging stored energy to operate portable wireless listening device  230 . The discharged energy can be used to power the electrical components of portable wireless listening device  230 . In some embodiments, battery  238  can be a rechargeable battery that enables the battery to be repeatedly charged as needed to replenish its stored energy. For instance, battery  238  can be coupled to battery charging circuitry (not shown) that is operatively coupled to receive power from charging case interface  239 . Case interface  239  can, in turn, electrically couple with earbud interface  252  of charging case  250 . In some embodiments, power can be received by portable wireless listening device  230  from charging case  250  via electrical contacts within case interface  239 . In some embodiments, power can be wirelessly received by portable wireless listening device  230  via a wireless power receiving coil within case interface  239 . 
     Charging case  250  can include a battery  258  that can store and discharge energy to power circuitry within charging case  250  and to recharge the battery  238  of portable wireless power listening device  230 . As mentioned above, in some embodiments circuitry within earbud interface  252  can transfer power to portable wireless listening device  230  through a wired electrical connection between contacts in charging case  250  that are electrically coupled to contacts in portable wireless listening device  250  to charge battery  238 . While case  250  can be a device that provides power to charge battery  238  through a wired interface with device  230  in some embodiments, in other embodiments case  250  can provide power to charge battery  238  through a wireless power transfer mechanism instead of or in addition to a wired connection. For example, earbud interface can include a wireless power transmitter coil that can couple with a wireless power receiving coil within portable wireless listening device  230 . 
     Charging case  250  can also include a case computing system  255  and a case communication system  251 . Case computing system  255  can be one or more processors, ASICs, FPGAs, microprocessors, and the like for operating case  250 . Case computing system  255  can be coupled to earbud interface  252  and can control the charging function of case  250  to recharge batteries  238  of the portable wireless listening devices  230 , and case computing system  255  can also be coupled to case communication system  251  for operating the interactive functionalities of case  250  with other devices, including portable wireless listening device  230 . In some embodiments, case communication system  251  includes a Bluetooth component, or any other suitable wireless communication component, that wirelessly sends and receives data with communication system  234  of portable wireless listening device  230 . Towards this end, each of charging case  250  and portable wireless listening device  230  can include an antenna formed of a conductive body to send and receive such signals. Case  250  can also include a user interface  256  that can be is operatively coupled to case computing system  255  to alert a user of various notifications. For example, the user interface can include a speaker that can emit audible noise capable of being heard by a user and/or one or more LEDs or similar lights that can emit a light that can be seen by a user (e.g., to indicate whether the portable listening devices  230  are being charged by case  250  or to indicate whether case battery  258  is low on energy or being charged). 
     Host device  210 , to which portable wireless listening device  230  is an accessory, can be a portable electronic device, such as a smart phone, tablet, or laptop computer. Host device  210  can include a host computing system  212  coupled to a battery  214  and a host memory bank (not shown) containing lines of code executable by host computing system  212  for operating host device  210 . Host device  210  can also include a host sensor system  215 , e.g., accelerometer, gyroscope, light sensor, and the like, for allowing host device  210  to sense the environment, and a host user interface system  216 , e.g., display, speaker, buttons, touch screen, and the like, for outputting information to and receiving input from a user. Additionally, host device  210  can also include a host communication system  218  for allowing host device  210  to send and/or receive data from the Internet or cell towers via wireless communication, e.g., wireless fidelity (WiFi), long term evolution (LTE), code division multiple access (CDMA), global system for mobiles (GSM), Bluetooth, and the like. In some embodiments, host communication system  218  can also communicate with communication system  234  in portable wireless listening device  230  via a wireless communication link  262  so that host device  210  can send audio data to portable wireless listening device  230  to output sound, and receive data from portable wireless listening device  230  to receive user inputs. The communication link  262  can be any suitable wireless communication line such as Bluetooth connection. By enabling communication between host device  210  and portable wireless listening device  230 , wireless listening device  230  can enhance the user interface of host device  210 . 
     1. Earphones 
     Portable wireless devices according to some embodiments can include a number of different features that provide a user with improved audio quality and a superior user experience as compared to many previously known portable wireless devices. To illustrate and explain some such features, reference is first made to  FIGS.  3 A- 3 C , which are simplified views of a wireless earphone  300 . Specifically,  FIG.  3 A  illustrates a front perspective view of a portable listening device according to an embodiment of the disclosure;  FIG.  3 B  illustrates a rear perspective view of the portable listening device shown in  FIG.  3 A ; and  FIG.  3 C  illustrates a front perspective view of the portable listening device shown in  FIG.  3 A  with its ear tip removed. Those skilled in the art will readily appreciate that the description of earphone  300  in  FIGS.  3 A- 3 C  is provided for illustrative purposes only and that, as discussed above, while earphone  300  is an in-ear headphone that represents a specific example of a portable listening device according to some embodiments, embodiments of the invention are not limited to in-ear headphones or to the specific features of earphone  300  as discussed below. 
     Earphone  300  can include a housing  310  and an ear tip  320  that can direct sound from an internal audio driver (e.g., a speaker) out of housing  310  and into a user&#39;s ear canal. Housing  310  can be made from, for example, a hard radio frequency (RF) transparent plastic such as acrylonitrile butadiene styrene (ABS) or polycarbonate. In some embodiments, housing  310  can be made from one or more components that can be bonded together (e.g. with tongue and groove joints and an appropriate adhesive) to form a monolithic housing structure with a substantially seamless appearance. 
     Housing  310  can include a speaker housing  312  and a stem  314  extending from the speaker housing  312  at an angle. Stem  314  can be substantially cylindrical in construction, but it can include a planar region  330  that does not follow the curvature of the cylindrical construction. Planar region  330  can indicate an area where the wireless listening device is capable of receiving user input. For instance, a user input can be inputted by squeezing stem  314  at planar region  330  or sliding a finger along a portion of the planar region. Stem  314  can also include electrical contacts  340  and  342  for making contact with corresponding electrical contacts in charging case that can store and charge a pair of earphones  300 . Electrical contacts  340 ,  342  provide a physical interface that can be electrically coupled with corresponding electrical contacts in a corresponding charging case (e.g., charging case  150 ). It is to be understood that embodiments are not limited to the particular shape and format of the housing  310  depicted in  FIGS.  3 A- 3 C . For example, in some embodiments the housing does not include a stem or similar structure and in some embodiments an anchor or other structure can be attached to or extend away from the housing to further secure the earbud to a feature of the user&#39;s ear. 
     Also shown in  FIG.  3 A  is cap  346  that is part of overall housing  310  and can be affixed to an end of stem  314  forming a water tight seal with the stem. A bottom microphone (not shown) can be attached to an interior surface of cap  346  and the cap can include an acoustic port (not shown) that allows the microphone to capture sounds from the environment. Cap  346  can also include two seats along its external surface on opposite sides of the cap for the two contacts  340 ,  342 . The two seats can be recessed a sufficient amount such that the contacts  340 ,  342  can be secured to the seats and positioned flush with an outer surface of cap  346  creating a smooth, seamless structure that has an improved appearance and reliability. An electrical connection to circuitry within stem  314  can be made to each of contacts  340 ,  342  through an appropriate cutout or opening in cap  346  that can be covered by the contacts. 
     In some embodiments housing  310  can be formed of a seemingly monolithic outer structure without any obvious seams or rough edges. Housing  310  can form a shell that defines an interior cavity (not shown) in which the various components of earphone  300  are positioned. For example, enclosed within housing  310  can be a processor or other type of controller, one or more computer-readable memories, wireless communication circuitry, an antenna, a rechargeable battery, power receiving circuitry and various sensors, such as an accelerometer, a photodetector, force and touch sensors and the like, none of which are shown in any of  FIGS.  3 A- 3 C . Housing  310  can also house an audio driver (i.e., a speaker) and one or more microphones. The speaker and one or more microphones can each be positioned within housing  310  at locations adjacent to audio openings that extend through housing  310  to allow the speaker and the one or more microphones to transmit and receive audio waves through the housing. 
     Some or all of such audio openings can be covered by a mesh. For example, as shown in  FIG.  3 C , a mesh  350  can be disposed over an audio port formed in speaker housing  312 . A speaker can be positioned within the speaker housing and aligned to emit sound through the audio port, through mesh  350  and through a central channel  322  that extends through ear tip  320  into a user&#39;s ear canal. As another example, a rear vent can be formed through speaker housing  312  and covered with a mesh  352 . The rear vent can be acoustically coupled to a back volume of the speaker housing to provide improved acoustic performance of the earphone. As still another example, a microphone port can formed through housing  310  at a location where speaker housing  312  and stem  314  are joined and covered by a mesh  354 . A microphone can be disposed within housing  310  at a location adjacent to the microphone port such that the microphone can receive sound waves through mesh  354  and through the microphone port. 
     Earphone  300  can also include an optical sensor  356  that can be used to determine when the earphone is being worn within a user&#39;s ear. The optical sensor  356  can be strategically positioned at a location along housing  310  that is likely to be in contact with or directly facing an inner surface of the average user&#39;s ears when the earphone is worn by the user. In this manner, the optical sensor can be used, sometimes in conjunction with other sensors, to determine whether earphone  300  is worn by a user and positioned within the user&#39;s ear as discussed in more detail below. In some embodiments, the optical sensor can be positioned behind an optically transparent window that is positioned along speaker housing  310 . 
     Ear tip  320  can be made primarily from a deformable material and can be sized and shaped to fit within a user&#39;s ear canal In the embodiment depicted in  FIGS.  3 A- 3 C , ear tip can be removably attached to speaker housing  310  and is shown in  FIG.  3 A  in an attached state and in  FIG.  3 C  in a detached stated. 
     2. Front Porting for ANC 
     One benefit that a deformable ear tip, such as ear tip  320 , provides is that when the ear tip is inserted into a user&#39;s ear canal, the ear tip can form a seal with the inner wall of the ear canal attenuating or blocking out external noises. The seal between a deformable ear tip and the user&#39;s ear canal can form a closed acoustic architecture that enables the in-ear headphone to have improved noise cancellation features as opposed to earphones that have an open acoustic architecture. 
     Some embodiments described herein pertain to earphones that have a deformable ear tip that enable a closed acoustic architecture with improved active noise cancellation. To illustrate, reference is first made to  FIG.  4   , which is a simplified cross-sectional illustration of an in-ear earphone  400 . Earphone  400  includes a housing  420  an ear tip  430 . As shown in  FIG.  4   , earphone  400  is being worn by a user with ear tip  430  inserted into an ear canal  410  of the user&#39;s ear and spaced apart from the user&#39;s ear drum  412 . Earphone  400  represents a previously known earphone. 
     Housing  420  includes a nozzle  425  to which ear tip  430  can be removably attached. An audio driver  422  and microphone  424  are positioned within housing  420  and/or nozzle  425  that defines an audio port through which audio driver  422  can deliver sound. When ear tip  430  is coupled to nozzle  425 , sound can travel from driver  422 , through nozzle  425  and through an audio channel  434  formed in ear tip  430  to a user&#39;s ear drum. Nozzle  425  and ear tip  430  can include meshes  426  and  432 , respectively, that extend across and cover an audio channel that extends through the nozzle and ear tip to prevent debris and earwax from invading housing  420 . During use, a slight pressure can sometimes build up within ear canal  410  that some users find uncomfortable. To reduce such pressure, ear tip  430  can include a pressure leak path  436  that can be through, for example, one or more small openings in a wall of the ear tip that enable pressure from within ear canal  410  to escape to the ambient environment. 
     Microphone  424  can be employed in conjunction with circuitry (not shown) within the earphone  400  to implement an active noise canceling feature. Microphone  424  can be attached to housing  420  by a bridge  428 , which is positioned between microphone  424  and the distal end of nozzle  425 . An acoustic path  440  between ear drum  412  and microphone  424  extends through ear canal  410 , ear tip  430  and meshes  432 ,  426 , and around an outer periphery bridge  428  before reaching an audio opening of microphone  424 , which can in itself be covered with a separate mesh or membrane as shown by the dotted line. 
     The inventors have found that in an ideal situation for noise canceling, the acoustic path between microphone  424  and ear drum  412  should be as short as possible to reflect any leakage that might occur either between the ear tip and ear canal or when there is an intentionally added leak path, such as pressure leak path  436 . Embodiments disclosed herein provide an improved noise cancelling capabilities by shortening the acoustic path  440  without changing the structure of housing  420  or ear tip  430 .  FIG.  5    is a simplified cross-sectional illustration of an in-ear earphone  500  in accordance with some embodiments. Earphone  500  can include many of the same features as earphone  400  including, among others, housing  420 , audio driver  422 , microphone  424 , nozzle mesh  426 , ear tip  430  and ear tip mesh  432 . Thus, for ease of explanation, the same reference numbers are used in  FIG.  5    as used in  FIG.  4    to indicate like elements. Also, similar to earphone  400  in  FIG.  4   , earphone  500  is depicted in  FIG.  5    as being worn by a user with ear tip  430  inserted into an ear canal  410  of the user&#39;s ear and spaced apart from the user&#39;s ear drum  412 . 
     As shown in  FIG.  5   , the acoustic path  540  between microphone  424  and a user&#39;s earbud  412  is more direct and shorter in earphone  500  than the similar acoustic path  440  in earphone  400 . One difference between the two earphones is that bridge  528 , which couples microphone  424  to housing  420  in earphone  500 , includes a passageway  542  that extends between opposing upper surfaces of the bridge. Thus, acoustic pathway  540  extends directly through bridge  528  to get to microphone  422  rather than being diverted around an outer periphery of bridge  428  to get to the microphone as required in earphone  400 . Allowing the acoustic pathway  540  to traverse bridge  528  through passageway  542  enables microphone  424  to be joined directly to a lower surface of bridge  528  thereby eliminating the gap X present between microphone  424  and bridge  428  in earphone  400  and moving the microphone closer to ear drum  412  further shortening the acoustic pathway  540 . 
       FIGS.  6 A and  6 B  are simplified top plan and cross-sectional views of a portion of earphone  500  that includes nozzle  425 . The nozzle  425  defines an audio port  600  that opens to the interior cavity of earphone housing  420 . Mesh  426 , which his not included in  FIG.  6 A  to better illustrate other elements, extends across audio port  600  preventing debris and earwax from entering the interior of housing  420 . Bridge  528  is positioned directly beneath the mesh  426  and can be mechanically attached to the wall of nozzle  425 . Microphone  424  can be coupled to the bottom surface of bridge  528  such that an opening  610  to the microphone is aligned with passageway  542  through the bridge  528 . A hydrophobic mesh  620  can be positioned between the microphone  424  and the bridge  528  and extend over the microphone opening  610  to prevent moisture and other particles that get past mesh  426  from entering the microphone. One or more adhesive layers (not shown), such as a PSA layer, can be disposed between the hydrophobic mesh and each of the bridge  528  and microphone  424  to secure the components together. In some embodiments, an airtight seal can be formed between microphone  424  and the bottom surface of bridge  528  to ensure that sounds that reach microphone  424  do so through passageway  540 . 
     While passageway  542  in the embodiment depicted in  FIG.  6 B  provides a direct line-of-sight path through the bridge  528  to the microphone  424 , in other embodiments passageway  542  can have one or more bends along the length of the passageway creating a tortuous path from an upper surface of bridge  528  to microphone opening  610 . Such a tortuous path can provide further protection to the microphone  424  against particles or other foreign objects from penetrating into the microphone and/or the acoustic membrane  620 . In some embodiments, microphone  424  is joined to the bottom surface of bridge  528  with an airtight seal to ensure that sounds that reach microphone  424  do so through passageway  540 . 
     3. Rear Vent and Mesh 
     Earphones according to various embodiments can include one or more openings that extend through an outer wall of the earphone housing. Different openings can serve different purposes. For example, a primary audio port can allow the speaker to transmit sound towards a user&#39;s ear, other openings can enable microphones to transmit and receive audio waves through the housing and still other openings can enable improved audio performance of the earphone. Some or all of such audio openings can be covered by a protective mesh as discussed with respect to  FIGS.  3 A- 3 C . 
     As a specific example of a protective mesh, a rear vent can be formed through speaker housing  312  and covered with a mesh  352  as shown in  FIG.  3 A . The rear vent can be acoustically coupled to a back volume of the speaker housing  312  to provide improved acoustic performance of the earphone. The protective mesh  352  can extend over the rear vent to prevent ear wax or particles from entering the housing through the rear vent. The protective mesh can be formed as a multi-layered structure including a cosmetic mesh and an acoustic mesh where the cosmetic mesh forms an outer surface of earbud  300  and is formed of an interlaced network of stiff wire, while the acoustic mesh is positioned within acoustic port  314  beneath the cosmetic mesh and is formed of a porous fabric. As a specific non-limiting example, the cosmetic mesh can be formed of interlaced stainless steel and the acoustic mesh can be formed of polyester. 
     Because earphones are worn directly in a user&#39;s ear, earphones are susceptible to a build-up or collection of wax that can collect on any or all of the meshes. Such wax can be particularly problematic on the meshes that come in physical contact with a portion of the ear, such as the mesh  352  formed over the rear vent. Wax build-up on mesh  352  can occlude the rear vent opening which can adversely impact the sound quality of an earphone. Earphones in accordance with some embodiments include an improved multi-layer mesh structure that reduces the impact of any potential wax build-up. 
       FIG.  7    is a simplified cross-sectional view of a portion of an earphone  700  in accordance with some embodiments. Earphone  700  includes a rear vent  710  formed through a wall of a housing  720 . A multi-layer protective mesh  730 , which can be representative of mesh  352 , covers rear vent  710 . Mesh  730  can include an outer cosmetic mesh  732  disposed over a separate acoustic mesh  734 . Importantly, acoustic mesh  734  is spaced apart from cosmetic mesh  732  in a central portion of rear vent  710 . During use of earphone  700 , ear wax can collect around the outer periphery of cosmetic mesh  732 . As wax builds-up on the mesh, the wax can spread inward and eventually completely occlude rear vent  710 . The spacing between acoustic mesh  734  and cosmetic mesh  732  allows more wax to collect on the cosmetic mesh before any such collected wax would completely occlude rear vent  710 . Thus, the spacing increases the time to a possible occlusion event, which in turn reduces the frequency in which the multi-layer mesh  730  needs to be cleaned. As shown in  FIG.  7   , cosmetic mesh  732  can have a convex shape such that a center portion of the mesh protrudes further towards an exterior surface of earphone  700  than the peripheral portions of mesh  732 . 
     In other embodiments, the cosmetic mesh can have a concave shape as shown in  FIG.  8   , which is a simplified cross-sectional view of a portion of an earphone  800  in accordance with some embodiments. As shown in  FIG.  8   , earphone  800  includes a rear vent  810  formed through a wall of a housing  820 . A multi-layer protective mesh  830 , which can also be representative of mesh  352 , covers rear vent  810 . Similar to mesh  730 , mesh  830  can include an outer cosmetic mesh  832  disposed over an acoustic mesh  834  that is spaced apart from the cosmetic mesh  832  in a central portion of rear vent  810 . The spacing between the two mesh layers allows more wax to collect on cosmetic mesh  832  before any such collected wax would completely occlude rear vent  810 . Unlike cosmetic mesh  732 , cosmetic mesh  832  has a concave shape to it such that the central portion of mesh  832  is spaced further from an exterior surface of earphone  800  than the peripheral portions of mesh  832 . The concave shape creates a deeper, sub-flush mesh where the extra depth can further increase time to a possible occlusion event, which in turn can further reduce the frequency in which the multi-layer mesh  830  needs to be cleaned. The central portion of mesh  550  can still be recessed from the exterior surface of speaker housing  310  by a distance X, which in some embodiments can be between 0.1 and 1.5 mm. 
       FIGS.  9 A and  9 B  are simplified cross-sectional and exploded perspective views, respectively, of a multi-layer mesh  930  that can be representative of multi-layer mesh  830 . In  FIG.  9 A , multi-layer mesh  930  is shown within a rear-vent  910  formed through a housing  920  of an earphone  900 . Multi-layer mesh  930  includes an outer cosmetic mesh  932  and an inner acoustic mesh  934 . A stiffener  938  provides support for the acoustic mesh, which can be bonded to stiffener  9386  by an adhesive layer  936 , such as a pressure sensitive adhesive (PSA) layer. An acoustic frame  922  sits within housing  920  and can provide an indirect, sealed path  940  between rear vent  910  and the back volume (not shown) of the audio driver. The indirect path  940  can take the form of an elongated tubular acoustic passageway that can improve passive attenuation of earphone  900 . The sealed tubular passageway can take a tortuous path between rear vent  910  and the back volume with bends in the path having curved edges to improve acoustic airflow and reduce “choking”. In some embodiments, the tube dimensions can maintain a ratio of 0.8 height×2.0 width x 3.5 functional length, and in some particular implementations, the tube dimensions can have a minimum height of about 0.8 mm. 
     4. User-Interaction: Pressure and Touch Sensing 
     Earphones according to some embodiments can include a user-input device positioned along an exterior surface of the earphone housing. In some embodiments, the user-input device can be a touch sensitive and pressure sensitive surface along a stem portion of the earphone housing, such as planar region  330  positioned along stem  312  of the earphones  300  depicted in  FIGS.  3 A- 3 C .  FIG.  10 A  is a simplified rear perspective view of an earphone  1000  according to some embodiments. Earphone  1000  can be representative of earphone  300  and includes a housing  1010  having a speaker housing portion  1012  and a stem portion  1014 . 
     As shown in  FIG.  10 A , stem  1014  has a substantially cylindrical in construction but the stem can have any appropriate shape in other embodiments. Stem  1014  defines an interior cavity (region  1045  shown in  FIGS.  10 B and  10 C ) extending along a length of the stem in which components of earbud  1000  are positioned. A planar region  1030  that does not follow the curvature of the cylindrical construction is disposed along a lower portion of stem  1014  between a distal end  1016  of the stem and a mesh  1054 . The mesh  1054  overlies an audio port (not shown in  FIG.  10   ) and a microphone (also not shown) disposed within housing  1010  at a location adjacent to the microphone port such that the microphone can receive sound waves through mesh  1054  and through the microphone port. Planar region  1030  can provide a tactile surface that indicates to a user an area where the earphone  1000  is capable of receiving user input. For instance, a user input can be inputted by squeezing stem  1014  at planar region  1030  or by sliding a finger along a portion of planar region  1030 . A person of skill in the art will appreciate that planar region  1030  can be replaced by or enhanced by one or more other features that provide additional and/or improved tactile feedback including, as examples, bumps, grooves, recesses, etc. 
       FIGS.  10 B and  10 C  are simplified cross-sectional views of portions of stem  1030  along the different sections of the stem as indicated in  FIG.  10 A . As shown in the  FIGS.  10 B and  10 C , planar region  1030  is present in  FIG.  10 B  but not in  FIG.  10 C .  FIG.  10 B  also shows a flex circuit board  1040  disposed adjacent to the planar surface  1030 . Circuit board  1040  can include both force and touch sensors as described in more detail in conjunction with  FIGS.  11 A- 11 C  below. Circuitry, such as an antenna  1080  that can extend along a majority of a length of the stem and system in a package (SIP)  1082 , can also be disposed within interior region  1045  of stem  1014 . SIP  1082  can include an ASIC that drives and monitors the force and touch sensors. In some embodiments, SIP  1082  or other separate circuitry disposed within region  1045  can further include: a main processor that controls the operation of earbud  1000 ; one or more computer-readable memories; charging circuitry; additional sensors, such an accelerometer, a gyroscope; a wireless communication controller; support components for antenna  1080 ; and uplink and downlink communication circuitry; among others. Including the SIP and its associated circuitry in stem portion  1014  of earbud  1000  enables the speaker housing portion  1012  to be smaller than it otherwise would be (while including an appropriate sized battery). 
     Reference is now made to  FIGS.  11 A- 11 C  that depict various views of an earphone  1100  according to some embodiments. Earphone  1100  can be representative of any of the earphones discussed above including earphone  300  and earphone  1000 .  FIGS.  11 A and  11 B  are each simplified cross-sectional views at different depths along a length of a stem  1114 , and FIG.  11 C is a simplified cross-sectional illustration along the stem depicting a relationship between touch pixels and sense pixels within the stem. As shown in  FIG.  11 A , a planar region  1130  is disposed along stem  1114  and multiple touch pixels can be disposed directly under the surface of the planar region  1130 . In the embodiment depicted in  FIG.  11 A , three separate and distinct capacitive touch pixels  1150 ,  1152  and  1154  are included in the touch region but embodiments are not limited to any particular number of touch pixels and other embodiments can include fewer than or more than three touch pixels. In some embodiments, the touch pixels can be built into copper layers formed in a flex circuit  1170  discussed below with respect to  FIG.  11 C . 
     As shown in  FIG.  11 B , which represents a cross-sectional view of planar region  1130  below the cross-sectional view depicted in  FIG.  11 A , a single capacitive force pixel  1160  is also disposed along stem  1114  directly under the surface of the planar region  1130  and directly under the touch pixels. While the embodiment depicted in  FIG.  11 B  includes just a single force pixel in the touch region, other embodiments are not limited to any particular number of force pixels and other embodiments can include more than one force pixels. 
     A user can provide input to earphone  1100  through either or both the touch pixels and the force pixel. For example, in some embodiments a user can slide his or her finger along stem  1114 , which can be detected by the touch pixels, to change the volume of an audio stream played over earphone  1100 . As another example, a user can squeeze stem  1114  at the planar region  1130 , which can be detected by the force pixel, to initiate a voice-activated, virtual assistant, such as Siri that is built into various Apple products, and/or answer a cellular telephone or other call over earphone  1100 . 
     The capacitive touch pixels and force pixel can be formed in or bonded to a common flex circuit  1170 , which in turn, can be laminated to an inner surface of stem wall  1116 . In some embodiments, the touch pixels  1152 ,  1154 ,  1156  can be formed directly on an upper surface of a flex circuit  1170  as shown in  FIG.  11 C  with their sensing surface facing outward toward wall  1116 , while the force pixel  1160  can be disposed on a lower surface of flex circuit  1170  in an opposite orientation facing inward. The force pixel can be arranged such that a foam layer  1184  fills the force sensor gap between the first and second capacitive pads  1186  and  1188  of the force pixel. Foam layer  1184  can be a high dielectric material and can mechanically secure the force sensor to antenna  1180 . When a user squeezes stem  1114  in the planar region  1130 , the flex  1170  is pushed toward electrode  1188  and the gap between the two electrodes  1186 ,  1188  is reduced creating a change in capacitance that can be detected generating a user-input signal that can be acted upon by electronics within earbud  1100  to carry out a predetermined function as noted above. 
     In some embodiments, first capacitor pad  1186  is formed as part of a copper layer or layers or as a conductive coating contained within or laminated to a bottom surface of flex circuit  1170  and the second capacitor pad  1188  of is built into the antenna ground. In other embodiments, first capacitor pad can be a conductive element bonded to flex circuit  1170  and/or both capacitor pads  1186  and  1188  can have a voltage on them in a mutual capacitance arrangement. 
     In some embodiments, flex circuit  1170  is laminated to the inner surface of wall  1116  using a low temperature curable adhesive (e.g., adhesive  1172 ). The accuracy of the capacitive touch pixels  1150 ,  1152  and  1154  can be dependent on the lamination process. The adhesive should be able to withstand internal stresses from spring back forces associated with squeezing the stem region to activate the force sensor. The inventors have found that a standard pressure sensitive adhesive can be inadequate in such circumstances as air bubbles can start to form over repeated use that can then interfere with the accuracy of the capacitive touch pixels. Instead, in some embodiments the adhesive is cross-linking adhesive formulated as b-stage system in which a first low temperature cure step partially cures the adhesive material and is followed by a UV cure step to fully cure the adhesive and bond the laminate to the wall. Additionally, to ensure a strong bond between wall  1116  and flex circuit  1170 , in some embodiments the flex circuit  1170  is a separate flex dedicated to the touch and force pixels. In this manner, flex  1170  can be inserted into stem  1114  and fully bonded to the inner surface of wall  1116  (e.g. by adhesive layers  1172  and  1174 ) prior to mechanically attaching other components to the stem. 
     Since both the touch pixels  1150 - 1156  and the force pixel  1160  are capacitive, shared sensor control circuitry, such as a single ASIC (not shown), within SIP  1182  can be used to control the operation of both the touch sensor and the force sensor. That is, the single ASIC can be operatively coupled to the both the touch and force sensor to excite the sensors at one or more frequencies and to detect signals from both sets of sensors. For example, the single ASIC can capture signals from both the touch pixels and the force pixel in the same time frame. Using shared sensor control circuitry, such as a single ASIC, to control both the touch and force sensors can save a considerable amount of battery power enabling earphones  1100  to be used longer between charges. 
     To further facilitate reducing battery power, earphones according to some embodiments can employ different modes of operation depending on whether the earphones are being worn in a user&#39;s ear, are inside their charging case or are out of the case but are off the user&#39;s ear and thus not being worn. Towards this end, embodiments of earphones disclosed herein can include one or more sensors (e.g., photodiodes, magnets, hall effect sensors, an accelerometer, and the like) that can detect whether an earphone is within a charging case or within a user&#39;s ear. 
       FIG.  12    is a state diagram  1200  depicting the different power modes according to some embodiments. As shown in  FIG.  12   , there are three primary states: In-case (state  1210 ), Off-ear (state  1220 ), and In-ear (state  1230 ). In-case states  1210  has two sub-states: low power sleep (sub-state  1212 ) and deep sleep (sub-state  1214 ), and in-ear state  1230  also includes two sub-states: active (sub-state  1232 ) and inactive (sub-state  1234 ). 
     To explain the power savings associated with the different states and sub-states, assume that a pair of earphones, such as any of earphones described herein including, but not limited to, earphones  300 ,  1000   1100 , have been stored in a charging case with the battery for each earphone fully charged overnight. In the morning, the earphones, still in the charging case, will be in a deep-sleep sub-state  1214  in which both the touch and the force pixels are turned fully OFF. When the user opens the lid to the charging case, the earphones switch from deep sleep sub-state  1214  to a normal sleep sub-state  1212  in which the touch pixels are maintained OFF but the force pixel is turn ON and sampled at a low, baseline rate to save power. In various embodiments the baseline rate can be less than 10 Hz, less than 5 Hz, less than 2 Hz or less than 1 Hz. In one particular implementation, the baseline rate can be 0.5 Hz. 
     When sensors within the earphone detect that it is first removed from its charging case, the earphone enters off-ear mode  1220  in which both the touch and the force sensors are sampled at the low, baseline rate. If the sensors detect that the earphone is then inserted into the ear of a user, the earphone can initially switch to an inactive sub-state  1234  in which the touch and force sensors are sampled is substantially increased to a standard mode rate. In inactive sub-state  1234 , the touch pixels are tied together into a single electrode to determine if a finger is present anywhere within the touch region and a baseline update is performed in the background at the baseline rate as described below in conjunction with  FIG.  13   . In various embodiments, the standard rate can be at least five times the baseline rate, at least ten times the baseline rate, at least fifty times the baseline rate or at least 100 times the baseline rate. In one particular implementation where the baseline rate is 0.5 Hz, the standard rate can be 60 Hz. 
     While in a user&#39;s ear, the earphone will remain in the inactive sub-state unless the touch pixels detect the presence of a finger, which can be done, for example, when the capacitance on the touch pixels is greater than a predetermined inactive threshold value. Once a finger is detected, the earphones switch to active sub-state  1232  in which the capacitance on the touch pixels can be independently measured on each touch pixel and the touch pixels and force pixel are sampled at the standard rate. The earphone can remain in active sub-state  1232  until either: (1) the capacitance on each touch pixel drops below a predetermined active threshold value and no touch was detected on any of the touch pixels for at least predetermined time period, which in some embodiments can be 500 msec, or (2) the earphone are removed from the user&#39;s ear in which case they are switched into off-ear state  1220 . 
     Further details of the manner and rate at which the touch and/or force pixels are sampled in inactive sub-state  1234 , in active sub-state  1232  and in the baseline update according to some embodiments are set forth in  FIG.  13   , which is a simplified timing chart depicting sequences of steps associated with each of the inactive and active sub-states and the baseline update process. As shown in  FIG.  13   , inactive sub-state  1234  includes two separate steps where the force pixel is sampled (step  1302 ) and then the touch pixels (step  1304 ). As noted above, instead of sampling each touch pixel individually, in order to save power, all the touch pixels can be electrically tied together by circuitry within flex  1170  and sampled together in step  1304 . If sufficient capacitance is detected on the combined touch pixel (e.g., capacitance greater than or equal to a first predetermined threshold) to indicate that a finger is positioned along the touch sensors, the earphone can be switched into active sub-state  1232 . If capacitance above the first predetermined threshold is not detected and the earphones are still within the ear of the user, the earphones will remain in the inactive sub-state and repeat sampling the force and combined touch pixels (steps  1302  and  1304 ) at the baseline frequency, which if 0.5 Hertz means the steps  1302  and  1304  are repeated every two seconds. 
     When earphones switch from inactive sub-state  1234  to active sub-state  1232 , the frequency at which the force and touch pixels are sampled substantially increases as noted above. For example, if the inactive sub-state samples the force and touch pixels at a rate of 0.5 Hz (once every two seconds) and the active rate samples the force and touch pixels at a rate of 60 Hz (60 times per second), the sampling frequency increases 120 times between the two states. In addition to increasing the sampling frequency, each touch pixel is looked at individually so the earphone can determine the location of a user&#39;s touch within the user input region (e.g., planar region  330 ). The higher sampling rate in the active sub-state allows the earphone to determine the direction a finger is moved across the user input region when a swipe motion is performed. 
     In addition to sampling the force and touch pixels, active sub-state  1232  includes a noise detection routine. When sampling the force and touch pixels, the earphone applies a voltage signal at an appropriate frequency that can be, for example, in the kilohertz range to one of the capacitor plates of each sensor. In some instances, an external source can create interference on the capacitor that could be wrongly interpreted by the earphone as a detection event. Thus, earphones according to some embodiments look for noise on the sensors and can implement a noise hopping scheme in which the voltage signal applied to the sensor capacitor plates is switched from a first frequency to a second frequency if noise above a predetermined threshold is detected on the first frequency. 
     As an example, when a user holds a smart phone up near his or her ear, circuitry within the smart phone can be in relative close proximity to an earphone in the user&#39;s ear and create noise within the earphone that might otherwise look like a detection event. To eliminate the possibility of noise incorrectly triggering a detection event, earphones according to some embodiments can choose between two different frequencies to excite (drive) the capacitors of the touch sensors and active sub-state  1232  can include two separate noise checks: a first noise check (step  1310 ) at frequency 1 and a second check (step  1314 ) at frequency 2. If noise is found on frequency 1 and not frequency 2, the touch pixels are driven (steps  1316 - 1322 ) at frequency 2. If noise is found on frequency 2 and not frequency 1, the touch pixels are driven (steps  1316 - 1322 ) at frequency 1. In the unlikely event that noise is found on both frequency 1 and frequency 2, the touch pixels can be temporarily blocked from controlling features of the earphone until the noise disappears from at least one of the two frequencies. In some particular implementations, frequency 1 is 200 KHz and frequency 2 is 510 KHz. As shown in  FIG.  13   , in some embodiments the noise check steps  1310  and  1314  are sandwiched around sampling the force pixel (step  1312 ). The sequence of the steps shown in  FIG.  13    for the inactive sub-state, active sub-state and the baseline update can be varied, however, and embodiments are not limited to any particular order of such steps. 
       FIG.  13    also illustrates the various steps associated with a baseline update process in which noise thresholds can be established for the sampling frequencies at which the touch sensors are driven. In some embodiments, an initial baseline update is performed when the earphones are still in their charging case upon detecting that the lid of the case is opened. The baseline process will check for noise on frequency 1 (step  1330 ) and scan the touch sensors at frequency 1 (steps  1332 - 1338 ) and then do the same for frequency 2 (noise check at step  1342  and touch sensor scans at steps  1444 - 1450 ). The amount of noise that is present on each frequency can then be taken into account when setting a threshold levels for registering a detection event on each frequency. Additionally, in some embodiments the baseline update can also include checking the force pixel (step  1340 ), which in  FIG.  13    is shown as being performed between the two frequency scans as an example timing sequence. The baseline update can then be repeated during active sub-state  1332  at the slower, baseline rate in order to maintain a baseline for noise at the frequency that is not being used to drive the touch pixels at that time. 
     5. Double-Flange Ear Tip 
     Ear tips that are in common use today are typically a monolithic structure made from a deformable material (e.g. silicone or a thermoplastic elastomer). As an example,  FIG.  14    is a simplified cross-sectional view of a typical deformable ear tip  1400 . Ear tip  1400  includes an inner ear tip body  1410  and an outer ear tip body (sometimes referred to as a flange)  1420  that together form a monolithic structure. Inner ear tip body  1410  is centered along a central axis  1415  and defines a sound channel that extends through the entire length of ear tip  1400 . The sound channel is an empty space through which sound travels from an audio driver within the earphone to which ear tip  1400  is attached to a user&#39;s eardrum. Outer ear tip body  1420  is attached to inner ear tip body  1410  at one end of the ear tip  1400  (an ear interfacing end) and extends outwardly towards the second, opposite end of ear tip  1400  creating a gap or vacant space  1425  between the outer and inner ear tip bodies along at least a portion of a length of ear tip  1400 . 
     When ear tip  1400  is inserted into an ear canal, outer ear tip body  1420  can bend into vacant space  1425  and conform to the contours of the ear canal to form an acoustic seal to prevent sound from entering the ear canal as ambient noise. Some surfaces of the ear canal can cause the outer ear tip body to unevenly press against the ear canal, which can create pressure points and cause discomfort. Additionally, only some portions of the outer ear tip body might make contact with the ear canal, thereby forming a weak seal that can allow noise from the environment to interfere with sound delivered by the earphone. 
     In some embodiments, the earphones described herein can include a second flange structure between the outer ear tip body and the inner ear tip body to provide improved user comfort and improved acoustic performance. The second flange structure can resist uneven deformation of the outer ear tip body so that pressure is spread evenly across the inner surface of the ear canal, thereby mitigating the creation of pressure points to improve comfort and acoustic seal.  FIG.  15    is a simplified cross-sectional view of a double flange ear tip  1500  according to some embodiments. Ear tip  1500  can include an inner ear tip body  1510  and an outer ear tip body  1520  that is sometimes referred to herein as outer flange  1520 . Inner ear tip body  1510  is centered along a central axis  1515  and defines a sound channel that extends through the length of ear tip  1500 . 
     Ear tip  1500  can include a tip region  1502  and a base region  1504 . Tip region  1502  can be a part of ear tip  1500  that inserts into the ear canal of a user while base region  1504  can be a part of ear tip  1500  that extends toward and attaches to a housing (e.g., a nozzle or similar outer structure) of an earphone. In some embodiments, the attachment region includes an attachment structure  1540  for securely attaching ear tip  1500  to a corresponding earphone. As mentioned herein, the inner and outer ear tip bodies can be formed from a compliant material that enables the ear tip to be inserted within and form a seal with the ear canal. Compliant materials may not easily attach to stiff structures such as a housing of an earphone. Thus, attachment structure  1540  can be included in some embodiments to provide rigidity to the base region  1504  of ear tip  1500  enabling the ear tip to be securely to an earphone housing. 
     Outer ear tip body  1520  can be a part of tip region  1502 . The outer ear tip body  1520  is attached to inner ear tip body  1510  at an ear-interfacing end  1506  of the ear tip  1500  and extends outwardly towards an earphone attachment end  1508  creating a gap  1525  between the outer and inner ear tip bodies along at least a portion of a length of ear tip  1500 . Ear tip  1500  further includes an inner flange structure  1530  that is connected at a first end  1532  to inner ear tip body  1510  at a point between ear interfacing end  1506  and attachment end  1508 . Inner flange structure  1530  extends into gap  1525  between inner ear tip body  1510  and outer ear tip body  1520  and can include a second end  1534  that contacts a distal portion  1526  of outer ear tip body  1520 . When ear tip  1500  is inserted into the ear canal, outer ear tip body  1520  can compress inward against inner flange structure  1530 . In some embodiments, second end  1534  is not fixedly attached to ear tip body  1520  and the lower portion  1528  of ear tip body  1520  can slide along the second end providing a force against the outer ear tip body  1520  that resists uneven deformation of outer ear tip body  1520 . In this manner, inner flange  1530  can enable an improved acoustic seal of the ear tip  1500  within the user&#39;s ear and a passive attenuation gain for improved acoustic performance. 
     In some embodiments, inner flange structure  1530  is a single continuous structure that fully surrounds an outer periphery of inner ear tip body  1510 . In other embodiments, inner flange structure  1530  can instead include multiple portions spaced apart from each other and formed radially around the outer periphery of inner ear tip body  1510 . Additionally, in some embodiments, such as the embodiment depicted in  FIG.  15   , a radius of curvature of inner flange  1530  as it extends away from inner ear tip body  1510  is greater than a radius of curvature of outer ear tip body  1520  extending away from inner ear tip body  1510 . The increased curvature of the inner flange  1530  minimizes potential sticking between the inner flange and outer ear tip body and also minimizes the possibility of inner flange  1530  becoming inverted. 
       FIG.  16    is a simplified cross-sectional view of a double flange ear tip  1600  according to some embodiments. Ear tip  1600  includes many of the same features as ear tip  1500  but outer ear tip body  1620  can be made from a material that has a different durometer than inner flange  1630 . For example, ear tip  1600  can be formed with a double shot injection molding process in which a first injection molding step of the process forms both a portion  1610   a  of the inner ear tip body and all of inner flange  1630 , and a second injection molding step of the process forms both a portion  1610   b  of the inner ear tip body and all of outer ear tip body  1620 . Inner ear tip body portion  1610   a  flange and inner flange  1630  can be made from a higher durometer material to provide more structure to the ear tip, while inner ear tip body portion  1610   b  and outer ear tip body portion  1620  can be made from a lower durometer material that is more flexible to provide a better and more comfortable user fit. 
     As can be appreciated herein, the outer ear tip body of ear tips according to some embodiments can press against an inner surface of an ear canal to form an acoustic seal. This acoustic seal can enhance the quality of sound experience by the user, but it can also sometimes trap pressure in the ear canal, potentially causing an unpleasant sensation to the user. Thus, in some embodiments, ear tips can include one or more control leaks  1650  for preventing the trapping of pressure in the ear canal while still enabling the outer ear tip body to form an acoustic seal. Control leak  1650  creates a pathway from the sound channel created within the inner ear tip body to the ambient environment that can reduce pressure build-up within the ear canal. In some embodiments, one or more control leaks  1650  can be formed in a rigid attachment structure  1640  as shown in  FIG.  16   , but in other embodiments one or more control leaks can be formed through the inner ear tip body. 
     Charging Case 
     Some embodiments described herein pertain to a charging case that can store and charge a portable electronic device, such as a wireless listening device or a pair of portable wireless listening devices, such as a pair of earphones  300 . The charging case can protect the portable electronic device or wireless listening devices from physical damage as well as provide a source of power for charging the electronic device or pair of wireless listening devices. 
       FIGS.  17 A- 17 C  are simplified plan views of a charging case  1700  that can store a pair of earbuds, such as earbuds  300 , according to some embodiments of the present disclosure. As shown in each of  FIGS.  17 A- 17 C , case  1700  can include a lid  1702  and a body  1704  that forms an internal cavity for housing a pair of wireless listening devices  300   a ,  300   b  that can be worn in a user&#39;s left and right ears, respectively.  FIGS.  17 A and  17 B  are front plan views of charging case  1700  and  FIG.  17 C  is a rear plan view of the charging case. Charging case  1700  is depicted in  FIG.  17 A  with lid  1702  in an open position while  FIGS.  17 B and  17 C  depict the charging case with the lid in a closed position. Lid  1702  can be attached to body  1704  by a hinge  1710  (shown in  FIG.  17 C ) that enables the lid to be moved between an open position (in which the earbuds  300   a ,  300   b  can be inserted into or removed from case  1700 ) and a closed position (in which the lid  1702  covers the earbuds  300   a ,  300   b  thereby completely enclosing the earbuds within the charging case  1700 ). 
     In some embodiments, charging case  1700  can include an internal frame (not visible in any of  FIGS.  17 A- 17 C ) including portions designed to provide contours and surface features against which wireless listening devices  300   a ,  300   b  can rest in strategic positions discussed herein to minimize the size of case  1700 . 
     To minimize the overall size of charging case  1700 , earbuds  300   a ,  300   b  can be positioned at strategic angles when placed in case  1700 . In some embodiments, each stem of the earbuds  300   a ,  300   b  is positioned at an angle with respect to two axis: an x-axis and a y-axis, instead of being positioned substantially vertically within the charging case. For purposes of description, the x-axis runs between earbuds  300   a ,  300   b , the y-axis runs between the front and the back of charging case  1700 , and the z-axis runs between the bottom of body  1704  and the top of lid  1702 . 
     Case  1700  can be configured to charge wireless listening devices  300   a ,  300   b  when they are housed in case  1700 . Towards this end, in some embodiments case  1700  can include two pairs of electrical contacts (not visible in  FIGS.  17 A- 17 C ) for making electrical contact with respective contacts on the stems of each earbud so that charge can flow from an internal battery (not shown) of case  1700  to internal batteries of the earbuds  300   a ,  300   b . The charging case internal battery can be charged by an external power supply that is electrically coupled to case  1700  via a connector  1706 . Connector  1706  can be any appropriate physical connector interface, such as a lightning connector port developed by Apple, a USB-C port, a mini USB port or the like. In some embodiments charging case  1700  also includes a wireless power receiving coil (not shown) to wirelessly receive power that can be used to charge the internal battery as discussed in more detail below. 
     In some embodiments charging case  1700  is highly resistant to moisture ingression and can be designed to meet IPX4 water resistance standards. Towards this end, electrical components within case  1700  (e.g., the charging case battery, the circuit board on which the processor and other electronic circuitry that controls the operation of the charging case, etc.) can be sealed within an internal system volume that is sealed with external system seals. Additionally, each electrical component can be sealed individually with a conformal coating or adhesive. Some embodiments can further include a barometric vent within the connector  1706  module that is permeable to air but not liquids. The barometric vent allows charging case  1700  to be tested, in the manufacturing line, immediately after manufacture of the case is completed to determine if the charging case is fully sealed in accordance with the manufacturer expectations, for example, in accordance with the IPX4 requirements. 
     Case  1700  can also include a visual indicator  1708  configured to emit different colors of light. Visual indicator  1708  can change colors depending on the charge status of the case. As an example, indicator  1708  can emit green light when the case is charged, emit orange light when the charging case battery is charging and/or when the charging case battery has less than a full charge, and red light when the charging case battery is depleted. When viewed from outside of case  1700 , visual indicator  1708  can have a circular shape, or any other suitable shape, such as square-like, rectangular, oval, and the like. Case  1700  can also include a user-interface  1712 , such as a button, that when activated and when the earbuds are stored within case  1700  with lid  1702  open, initiates a pairing routine that allows the earbuds to be paired with a host device. While indicator  1708  and button  1712  are shown in  FIGS.  17 B and  17 C  on front and rear case surfaces  1715  and  1720 , respectively, embodiments are not limited to any particular location for such user interfaces and these and other user interfaces can be positioned at any suitable exterior or interior surface of charging case  1700 . 
     Charging case  1700  can be relatively small (e.g., less than 2½ inches long, less than 2 inches high and less than 1 inch deep), which enables a user to easily take the case wherever he or she goes. With charging case  1700  being so portable, it can also become misplaced. An earphone charging case according to some embodiments can include an audio driver module and controller circuitry that enables a host device to communicate with location-based finding feature, such as Find My Device developed by Apple, Inc. 
       FIG.  18    is a simplified cross-sectional illustration of an earphone charging case  1800  according to some embodiments. Charging case  1800 , which and can be representative of charging case  1700 , includes a lid  1802  and a body  1804  that can be mechanically coupled to each other by a hinge (not shown). In some embodiments, each of lid  1802  and body  1804  can be hollow shells formed from a single continuous wall. For example, lid  1802  can a peripheral wall  1806  that defines both exterior and interior surfaces of the lid, while body  1804  can includes a peripheral wall  1808  that defines both exterior and interior surfaces of the body. A frame insert  1810  can fit within the peripheral wall  1808  and can include an insert wall  1812  that defines one or more cavities pockets for housing a pair of earphones, such as left and right earphones  300   a  and  300   b  or any of the earphones disclosed herein. As an example, in charging case  1800  frame insert  1810  can include a peripheral wall  1812  that defines contoured cavities  1806  and  1808  sized and shaped to accept a lower portion of earphones  300   a ,  300   b.    
     Frame insert  1810  can cooperate with peripheral wall  1808  to form a waterproof, sealed chamber  1815  within body  1804  in which various internal components of the charging case can be positioned. For example, charging case  1800  can also include circuitry  1820 , an antenna  1822  and a speaker module  1830  within the sealed chamber  1815 . Circuitry  1820  and antenna  1822  can be formed on a common support substrate, such as a printed circuit board (PCB). Circuitry  1820  can include, among other devices, a wireless communication circuitry and a controller mounted on the PCB. Antenna  1822  can be formed within a corner of charging case  1800  and in some embodiments can be an ultra-wideband antenna. The circuitry  1820  and antenna can cooperate to wirelessly send out a secure signal (e.g., a Bluetooth signal) that can be detected by nearby devices in the Find My network. The nearby devices can then send the location of charging case  1800  to an iCloud or similar server via a wireless network (e.g., a cellular or WiFi network). The server can then make charging case  1800  visible to approved devices that can display the location of charging case  1800  on a map. The approved devices can also communicate with charging case  1800  via the various wireless networks to send a signal to circuitry  1820  that puts charging case  1800  in a lost mode and/or to play a sound through speaker module  1830  to help a user locate the charging case. 
     In some embodiments, speaker module  1830  can generate a relatively loud beeping sound noise to assist as part of the Find My Device routine (or similar location-based find technique) and charging case  1800  includes a B-vent module  1840  to help ensure that air pressure within the speaker module  1830  is equalized to the air pressure external to charging case  1800  in order for speaker module  1830  to function properly. Further details of speaker module  1830  and B-vent module  1840  are discussed below with respect to  FIGS.  19 A and  19 B , respectively. 
     1. Speaker Module 
       FIG.  19 A  is a simplified cross-sectional illustration of a speaker module  1900  according to some embodiments that can be included in any of the earphone disclosed herein and can be representative of speaker module  1830 . As shown in  FIG.  19 A , speaker module  1900  includes an audio driver  1910  that has a speaker membrane  1912 , which is the dividing line between a front volume  1920  of audio driver  1910  and a back volume  1930  of the audio driver. Front volume  1920  is exposed to the outside air pressure through openings  1922  in a housing  1924  of the earphone in which speaker module  1900  is included. In some embodiments, openings  1922  can be, for example, three small circular holes formed through the housing  1924  but the openings are not limited to any particular shape or number. A cosmetic mesh  1925  and a water proof membrane  1926  can be attached (e.g., by a PSA layer  1928 ) across the openings  1922  to protect against debris and moisture ingress. As shown, cosmetic mesh  1925  can includes one or more small protrusions that extend from within housing  1924  into the openings  1922 . In some embodiments the protrusions can be flush with an exterior surface of housing  1924  or slightly recessed within the openings  1922 . 
     Front volume  1920  is sealed from back volume  1930  by various walls  1932  of speaker module  1900  and by seals  1934 , which can be, for example, an o-ring or a similar sealing structure. Back volume  1930  extends into the sealed chamber  1815  of body  1804  through a speaker vent  1940 , which can be covered with an acoustic membrane (not shown). Sealed chamber  1815  can be sealed with an airtight and waterproof seal to prevent moisture ingress into the body. Thus, back volume  1930  can be a completely enclosed and sealed space except for an opening to the outside environment through B-vent module  1940  as described below. 
     For speaker  1910  to provide a consistent volume and operation, the voice coil  1914 , which is operatively coupled to the speaker member, should be centered within a magnetic pole piece  1916  of audio driver  1910 . Such is the case when speaker membrane  1912  is in its nominal position  1942 . If pressure inside of the charging case is greater than the outside world pressure, however, speaker membrane  1912  can be undesirably pushed outwards into region  1944  moving the voice coil  1914  outside its ideal position. Conversely, if pressure inside of the charging case is less than the outside world pressure, speaker membrane  1912  can be undesirably pulled inward into region  1946 , which also moves the voice coil  1914  outside its ideal position. In some embodiments, charging case  1800  can include a B-vent module within the charging case that allows pressure to equalize between the front and back volumes  1920  and  1930 , respectively. 
     2. B-Vent 
       FIG.  19 B  is a simplified cross-sectional illustration of a B-vent  1950  according to some embodiments that can be included in any of the earphones disclosed herein and can be representative of B-vent module  1840  shown in  FIG.  18   . B-vent  1950  can include one or more openings  1952  formed through the same housing  1924  in which openings  1922  are formed. In some embodiments, for cosmetic reasons, openings  1952 , which can be on the right side of charging case  1800  can mirror openings  1922 , which can be on the left side. Thus, as an example, if there are three small circular openings  1922 , openings  1952  can also include three small circular openings having the same radius as openings  1922 . For the B-vent to function properly, only a single opening is needed for the vent itself. Thus, while  FIG.  18    shows three openings as part of the B-vent module  1840 , only the center opening  1952  is depicted in  FIG.  19 B  and the openings on the left and right of center opening  1952  can be sealed. 
     The B-vent opening  1952  provides an air path from speaker back volume  1930  through sealed chamber  1815  within body  1804  to the outside environment. A multi-layer mesh  1960  can cover opening  1952  preventing moisture and particles from entering the interior cavity of charging case  1800  while allowing air to cross the mesh. As shown in  FIG.  19 B , multi-layer mesh can include an outer cosmetic mesh  1962 , which as an example, can be a stainless steel mesh and an acoustic mesh  1964 . Similar to cosmetic mesh  1925 , cosmetic mesh  1962  can includes one or more small protrusions that extend from within housing  1924  into the openings  1952 . In some embodiments the protrusions can be flush with an exterior surface of housing  1924  or slightly recessed within the openings  1952 . 
     The multi-layer mesh  1960  can also include a clad between multiple layers including a non-woven thermoplastic layer and a hydrophobic layer. In one particular embodiment, multi-layer mesh  1960  can include a clad between a non-woven polyethylene terephthalate (PET) mesh layer  1966  and a hydrophobic, waterproof layer  1968  formed from Polytetrafluoroethylene (PTFE). Mesh layers  1962 ,  1964  and the clad of layers  1966 ,  1968  can be stacked on top of each other and bonded together by PSA layers  1970  and the multi-layer mesh  1960  can be mechanically attached to housing  1924  or other structural components of earphone  1800  by a hot melt bond  1972  formed around the perimeter of the multi-layer mesh  1960 . 
       FIG.  20    is a simplified perspective view of a charging case  2000  that can store a pair of earbuds, such as earbuds  300 , according to some embodiments of the present disclosure. As shown charging case  2000  includes a lid  2002  and a body  2004  that can be mechanically coupled to each other by a hinge (not shown). The hinge allows lid  2002  to be moved between an open position (in which the earbuds  300   a ,  300   b  can be inserted into or removed from case  2000 ) and a closed position (in which the lid  2002  covers the earbuds  300   a ,  300   b  thereby completely enclosing the earbuds within the charging case  2000 ). In some embodiments, each of lid  2002  and body  2004  can be hollow shells formed from a single continuous wall. 
     Charging case  2000  can be representative of charging cases  1700  and  1800  and can include some or all of the same features as those charging cases. Additionally, charging case  2000  can include an eyelet  2010  that is mechanically attached body  2004 . Eyelet  2010  can be made from metal, rigid plastic or another appropriate material and can include an outer surface that is generally flush with the outer surface of body  2004 . Eyelet  2010  can also include first and second openings  2012 ,  2014  that connect to a common cavity (not labeled) behind a neck portion  2016  of the eyelet. The eyelet can serve as an attachment point for a lanyard (not shown) to be connected to charging case  2000  (e.g., by threading a small wire or strap of the lanyard behind neck portion  2016  through the openings  2012 ,  2014 ). The lanyard can then be wrapped around a user&#39;s wrist (or neck if the lanyard is sized sufficiently) so that a user can more easily carry charging case  2000  without worrying about losing the charging case. 
     ADDITIONAL EMBODIMENTS 
     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. For example, while various examples of earphones described above were in the context of in-ear headphones that included deformable ear tips that can be inserted into a user&#39;s ear canal to form an airtight seal between the ear tip and the user&#39;s ear, various embodiments described herein are not limited to in-ear headphones. Thus, earphones according to some embodiments, can be configured to have an open, unsealed acoustic architecture that is sometimes referred to as a “leaky acoustic architecture” where the housing (e.g., speaker housing  310 ) can be sized and shaped to fit within a user&#39;s ear without having a deformable ear tip inserted into the ear canal. In such embodiments, all acoustic air volumes within the earbud have a free flowing air path to the ambient. 
     As another example, while embodiments of a multi-layer mesh that reduces the likelihood of occlusion events was described with respect to a rear vent, embodiments are not limited to any particular vent and a multi-layer mesh according to embodiments disclosed herein can be useful to protect the primary acoustic port, microphone openings and others. As still another example, while  FIGS.  17 A- 19 B  discussed embodiments of an charging case that can store and charge a pair of wireless earphones, other embodiments can pertain to a charging case for wired earphones or other portable electronic devices. 
     Thus, the foregoing descriptions of the specific embodiments described herein are presented for purposes of illustration and description. They are not target to be exhaustive or to limit the embodiments to the precise forms disclosed. Also, while different embodiments of the invention were disclosed above, the specific details of particular embodiments may be combined in any suitable manner without departing from the spirit and scope of embodiments of the invention. Further, 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. 
     Finally, it is well understood that the use of personally identifiable information should follow privacy policies and practices that are generally recognized as meeting or exceeding industry or governmental requirements for maintaining the privacy of users. In particular, personally identifiable information data should be managed and handled so as to minimize risks of unintentional or unauthorized access or use, and the nature of authorized use should be clearly indicated to users.

Metadata:
Filing Date: 20220824
Publication Date: 20240813
Grant Date: 20240813
Priority Date: 20220222
Inventors: COUSINS, Benjamin A.
LAGLER, JARRETT
SCHMELZER, DIRK
DE RIVAZ, SEBASTIEN D.
LI, TIAN SHI
QIAN, Phillip
RUSSELL, Rebecca
CHENGLEPUT SRINIVASAN, JEYAKKRISHNAN
WANG, JUE
GUTERMAN, Jerzy S.
YAMASAKI, JOEL C.
Assignee: APPLE INC
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Family ID: 87574894