Patent Publication Number: US-10334347-B2

Title: Earbud insertion sensing method with capacitive technology

Description:
TECHNICAL FIELD 
     Aspects and implementations of the present disclosure are directed generally to earbuds and to systems and methods for extending the battery life or controlling audio playback of same. 
     BACKGROUND 
     Earbuds for use with consumer electronic devices, for example, audio players and wireless communications devices (e.g., cell phones and personal data assistant devices incorporating cell phone capabilities) may be connected to an electronic device via a wired connection or wirelessly. Consumers generally prefer earbuds that are small and lightweight and comfortable to wear. Small and lightweight earbuds, however, can accommodate batteries of only a limited size and thus, a limited capacity. If a user accidentally powers on and sends audio to be played to an earbud while it is not in the ear of the user, or removes the earbud from the ear without first terminating rendering of audio by the earbud, battery life of the earbud may be unintentionally wasted. Further, it may be desirable to automatically control aspects of audio playback when the earbuds are placed in a user&#39;s ear or taken out of a user&#39;s ear. 
     SUMMARY 
     In accordance with an aspect of the present disclosure, there is provided an earbud. The earbud comprises a capacitive sensor including at least one conductive trace and a controller configured to provide an indication of the earbud being inserted into an ear of a user responsive to detecting changes in capacitance of one of the at least one conductive trace relative to ground or different conductive traces relative to one another. 
     In some implementations, the earbud further comprises a nozzle configured to be inserted into at least an entrance of an ear canal of the user and the at least one conductive trace is disposed on the nozzle. The at least one conductive trace may include portions extending at least partially about a perimeter of the nozzle. The earbud may further include a conductive element disposed within the nozzle. The controller may be configured to detect changes in capacitance between the conductive element and the at least one conductive trace. 
     In some implementations, the earbud further comprises an insulator disposed on the at least one conductive trace. 
     The earbud may further include redundant conductive traces and the controller may be configured to calibrate the capacitive sensor based on a capacitance between the redundant conductive traces. 
     In some implementations, the at least one conductive trace is constructed and arranged to exhibit a capacitance that increase with a depth of insertion of the earbud in the ear of the user. The controller may be further configured to provide an indication of the depth of insertion of the earbud in the ear of the user. The controller may be further configured to provide feedback to the user of whether the earbud is inserted into the ear of the user. 
     In some implementations, the controller is further configured to differentiate between signals from the capacitive sensor indicative of insertion of the earbud in the ear of the user and signals from the capacitive sensor indicative of manual handling of the earbud. 
     In some implementations, the controller is further configured to cause the earbud to transition from an active state to an inactive state responsive to the capacitive sensor providing a signal indicative of the earbud being removed from the ear of the user. 
     In some implementations, the controller is further configured to cause the earbud to transition from an active state to an inactive state responsive to the capacitive sensor failing to providing a signal indicative of the earbud being inserted into the ear of the user after a set time after activation of the earbud. 
     In accordance with another aspect, there is provided a method of reducing power consumption of an earbud. The method comprises determining whether the earbud is inserted into an ear of a user based on a measurement of capacitance of one of at least one conductive trace disposed on the earbud relative to ground or different conductive traces disposed on the earbud relative to one another and causing the earbud to transition from an active state to an inactive state responsive to determining that the earbud is not inserted into the ear of the user for more than a threshold amount of time. 
     In some implementations, the method further comprises causing the earbud to transition from the active to the inactive state responsive to failing to determine that the earbud is inserted into the ear of the user after a set time after the earbud is placed into the active state. 
     In some implementations, the method further comprises causing the earbud to transition from the active to the inactive state responsive to determining that the earbud has transitioned from a state in which the earbud is inserted into the ear of the user to a state in which the earbud is not inserted into the ear of the user. 
     In some implementations, the method further comprises determining a degree of insertion of the earbud into the ear of the user from the measurement of capacitance. The method may further comprise providing feedback to the user regarding the depth of insertion of the earbud into the ear of the user through one of the earbud or a device in communication with the earbud. 
     In some implementations, the method further comprises determining a degree of seal of the earbud in the ear of the user from the measurement of capacitance. The method may further comprise instructing the user to reposition the earbud to achieve a better seal of the earbud in the ear of the user. The method may further comprise modifying noise cancelling functionality of the earbud based on the degree of seal. 
     In some implementations, the method further comprises detecting movement of the earbud within the ear of the user based on the measurement of capacitance. 
     In some implementations, the method further comprises calibrating a capacitance meter in electrical communication with the at least one conductive trace by setting a reference capacitance at a capacitance detected between redundant traces disposed on the earbud. 
     In some implementations, the at least one conductive trace is disposed on an outside of a nozzle of the earbud and the method comprises obtaining the measurement of capacitance readings by measuring capacitance between the at least one conductive trace and a conductive element disposed within the nozzle. 
     In accordance with another aspect, there is provided a method of detecting insertion of an earbud into an ear of a user. The method comprises measuring a capacitance of one of at least one conductive trace disposed on the earbud relative to ground or different conductive traces disposed on the earbud relative to one another and providing an indication of the earbud being inserted into the ear of the user responsive to the capacitance exceeding a threshold capacitance value. 
     In some implementations, measuring the capacitance comprises measuring the capacitance between a set of conductive traces disposed on a nozzle of the earbud. 
     In some implementations, measuring the capacitance comprises measuring the capacitance between a conductive trace disposed on a nozzle of the earbud and a conductive element disposed with the nozzle. 
     In accordance with another aspect, there is provided an earbud. The earbud comprises a nozzle configured to be inserted into at least an entrance of an ear canal of the user. At least a portion of the nozzle comprises a set of stacked washers. The washers comprise cores of insulating material and conductive material disposed on faces of the washers. The conductive material disposed on the faces of the washers forms a set of conductive traces. The earbud further includes a controller configured to provide an indication of the earbud being inserted into an ear of a user responsive to detecting changes in capacitance of one of at least one conductive trace relative to ground or different conductive traces relative to one another. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component that is illustrated in various figures is represented by a like numeral. For purposes of clarity, not every component may be labeled in every drawing. In the drawings: 
         FIG. 1 a    is a perspective view of an example of in-ear audio device; 
         FIG. 1 b    is another perspective view of the example of the in-ear audio device of  FIG. 1   a;    
         FIG. 2 a    is an isometric view of an in-ear audio device headset; 
         FIG. 2 b    is an isometric view of another in-ear audio device headset; 
         FIG. 2 c    illustrates an example of a pair of wireless in-ear audio devices; 
         FIG. 2 d    is a perspective view in partial cross section of an example earpiece; 
         FIG. 3 a    is a partially cutaway view of the example of an in-ear audio device including a capacitive ear insertion sensor; 
         FIG. 3 b    is a partially cutaway view of another example of an in-ear audio device including a capacitive ear insertion sensor; 
         FIG. 3 c    illustrates an example of conductive traces of a capacitive sensor disposed on a canal portion of an in-ear audio device; 
         FIG. 3 d    illustrates another example of conductive traces of a capacitive sensor disposed on a canal portion of an in-ear audio device; 
         FIG. 3 e    illustrates another example of conductive traces of a capacitive sensor disposed on a canal portion of an in-ear audio device; 
         FIG. 3 f    is a cross-section of an example of a canal portion of an in-ear audio device formed from stacked washers; 
         FIG. 4 a    is an example of an eartip that may be utilized with various examples of in-ear audio devices disclosed herein; 
         FIG. 4 b    is another example of an eartip that may be utilized with various examples of in-ear audio devices disclosed herein; 
         FIG. 5  is a block diagram of an example of a controller for an in-ear audio device; and 
         FIG. 6  is a flow chart of a method for using examples of in-ear audio devices disclosed herein. 
     
    
    
     DETAILED DESCRIPTION 
     Aspects and implementations disclosed herein are not limited to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. Aspects and implementations disclosed herein are capable of being practiced or of being carried out in various ways. 
     Aspects and implementations disclosed herein may be applicable to a wide variety of audio devices structured to be at least partly inserted into one or both ears of a user (e.g., so called “in-ear” audio devices or “intra-aural” audio devices), hereinafter referred to also as “wireless earbuds” or simply “earbuds,” and audio players. The examples discussed herein are directed primarily to earbuds, which may be wired or wireless, but the technology disclosed may also have application to over-the-ear earphones or other audio devices. It should be noted that although specific implementations of wireless earbuds primarily serving the purpose of acoustically outputting audio are presented with some degree of detail, such presentations of specific implementations are intended to facilitate understanding through provision of examples, and should not be taken as limiting either the scope of disclosure or the scope of claim coverage. 
     Aspects and implementations disclosed herein may be applicable to earbuds that either do or do not support two-way communications, and either do or do not support active noise reduction (ANR). For earbuds that do support either two-way communications or ANR, it is intended that what is disclosed and claimed herein is applicable to an earbud incorporating one or more microphones disposed on a portion of the earbud that remains outside an ear when in use (e.g., feedforward microphones), on a portion that is inserted into a portion of an ear when in use (e.g., feedback microphones), or disposed on both of such portions. Still other implementations of earbuds to which what is disclosed and what is claimed herein is applicable will be apparent to those skilled in the art. 
     Various implementations and examples disclosed herein may provide for increased battery life in wireless earbuds by automatically causing the earbuds to turn off or deactivate when not in use. Further, various implementations and examples disclosed herein may provide for automatic control of audio playback in wired or wireless earbuds, for example to play audio when in use and pause audio when not in use. In some implementations, wireless earbuds are provided with one or more sensors that may be used to determine if the earbuds are inserted into the ear of a user. If a user removes an earbud from the ear of the user without first terminating rendering of audio by the earbud, the earbud may detect that it has been removed from the ear of the user and may automatically pause audio, or terminate rendering of audio and turn the earbud off, optionally after a set time after being removed from the ear of the user. In some implementations, if a user turns on an earbud and does not insert it into the ear of the user within a set time period, the earbud may automatically shut off. 
     In various implementations, earbuds may include one or more capacitive sensors. The one or more capacitive sensors may include conductive traces disposed on one or more portions of the wireless earbuds. The dielectric constant of the environment about the conductive traces is a factor that affects the capacitance between pairs of conductive traces or between the conductive traces and ground. The dielectric constant of human flesh is different than that of other materials or air and thus, as the conductive traces on an earbud are brought into proximity of the ear of a user, the capacitance between pairs of the conductive traces or between the conductive traces and ground changes. This change in capacitance may be detected by circuitry associated with the capacitive sensor or sensors. A degree of insertion of the earbud into the ear of a user may be determined by the capacitance between the conductive traces of the capacitive sensor or between the conductive traces and ground. Movement of the earbud into, out of, or from one position to another within the ear of the user may be determined by changes in capacitance between the conductive traces of the capacitive sensor or between the conductive traces and ground. The capacitive sensor may be calibrated to determine when an earbud is fully inserted into the ear of a user based upon measurements of capacitance between the conductive traces of the capacitive sensor or between the conductive traces and ground. Dummy or redundant conductive traces may be utilized to determine a baseline capacitance against which capacitance between the conductive traces or between the conductive traces and ground of the capacitive sensor used to detect insertion into the ear of the user may be compared to account for changes in moisture (e.g., sweat), eartips on the earbuds, or other environmental factors that may affect capacitance between the conductive traces or between the conductive traces and ground. 
     In some implementations, at least one conductive trace may be placed on a portion of an earbud that is designed to be inserted into the ear of a user during use, for example, an ear canal or nozzle portion of an earbud. Circuitry associated with the capacitive sensor may measure capacitance between one or multiple pairs of conductive traces or between at least one conductive trace and ground to determine, for example, whether the earbud is inserted into the ear of a user, if the earbud is fully inserted into the ear of the user, if the earbud forms an acceptable seal with the ear of the user, etc. In some implementations capacitance is measured between a conductive element disposed within or inside of the canal portion of the earbud and capacitive traces disposed on an external portion of the earbud, for example, the canal portion, in addition to, or as an alternative to measurements of capacitance between a pair or pairs of the conductive traces on the external portion of the earbud or between at least one of the conductive traces and ground. 
     In some implementations, acoustic processing circuitry associated with an earbud may modify one or more parameters of audio provided through the earbud based at least in part on a degree of fit or degree of insertion of the earbud into the ear of a user determined by the capacitance measurements made by the capacitive sensor. For example, the acoustic processing circuitry may modify one or more parameters of audio provided through the earbud to account for acoustic leakage associated with the earbud having a less than optimal degree of fit or insertion in the ear of the user. The one or more parameters of the audio may include, for example, volume or different equalization applied to different frequencies of audio rendered by the earbud. 
     Capacitive sensors in earbuds as disclosed herein may be used to manage battery life. The sensor could provide feedback on how well the earbud is seated in the ear canal of the user and adjust audio calibration accordingly. 
     The sensor output is specifically conducive to in-ear earbuds where it detects insertion inside the ear canal and not simply proximity to the ear. Detecting insertion of an earbud into an ear of a user rather than simply proximity of the earbud to the ear of the user is advantageous as it significantly reduces the pulse rate needed for detection to further improve battery life. An insertion detection method is an absolute threshold measurement that can be done infrequently. 
       FIGS. 1 a  and 1 b   , taken together, provide two views of one implementation of an earbud  100 .  FIGS. 1 a  and 1 b    are schematic representations of one possible earbud configuration. The ideas described herein apply to other configurations (for example, as shown in the additional figures included herein), so long as there is space (e.g., canal/nozzle portion) to put at least one conductive trace. The earbud  100  of  FIGS. 1 a  and 1 b    has a casing made up of at least a canal portion  110  (also referred to herein as a nozzle portion) meant to be positioned within at least an entrance of an ear canal of a user&#39;s ear and a concha portion  120  meant to be positioned within at least a portion of the concha of the user&#39;s ear. More specifically, and as depicted, the concha portion  120  has a curved shape to fit within the concha of a user&#39;s ear while accommodating the shape of the concha as defined by portions of the tragus, anti-tragus, and anti-helix of the pinna of the ear. This curved configuration has a pair of extensions  122  and defines an inner periphery  123 . The canal portion  110  has a generally tubular shape extending from where one end of the canal portion  110  is coupled to the concha portion  120  at a location coincident with where the entrance to the ear canal is typically located in relation to the portion of the concha defined by portions of the tragus and anti-tragus. An aperture  118  is formed in the other end of the canal portion  110  to enable sounds to be acoustically output by an acoustic driver (e.g., element  190  illustrated in  FIG. 3 a   ) positioned within the casing of the earbud  100  through the aperture  118  and into the ear canal when the earbud  100  is properly positioned in the ear of a user during operation. 
     The implementation of the earbuds  100  depicted in  FIGS. 1 a  and 1 b    may be any of a variety of types of earbuds able to perform any of a variety of audio functions including, and not limited to, an in-ear earphone to acoustically output audio, an in-ear ANR device to provide a reduction in environmental noise sounds encountered by a user through the acoustic output of anti-noise sounds, and/or a two-way communications audio device employing detection of the user&#39;s speech sounds through bone conduction and/or an Eustachian tube connected to portions of the ear into which the in-ear audio device  100  is inserted. Further, it should be noted that although the concha portion  120  has been depicted and described as having a curved shape to fit within the concha, other implementations are possible having a somewhat differently shaped concha portion  120  that does not fill as much of the concha, or fills more of the concha. 
     The earbud  100  may receive audio through a wired or wireless coupling with another device. Accordingly, electrical and electronic components such as, but not limited to, a wireless receiver and/or transmitter, processor (optionally including ANR circuitry), battery, microphone, and acoustic driver may be included within the concha portion  120  and/or canal portion  110  of the earbud  100 . Alternatively, such components may be included within a housing or casing coupled to the earbud. 
     Examples of earbuds  100  disclosed herein are not limited to the form factors illustrated in  FIGS. 1 a  and 1 b   . Other examples of form factors for earbuds are illustrated in  FIGS. 2 a -2 d   . The earbuds may be coupled by wiring as illustrated in  FIGS. 2 a  and 2 b    to form headsets or may be mechanically separate, as illustrated in  FIG. 2 c   . In various examples, the canal portion  110  or eartip may be separable from the concha portion  120  or may include a removable covering made of, for example, soft silicone to enhance comfort for a user. For example, in  FIG. 2 c   , section  100 A may include a rigid shell housing electronics such as an acoustic driver, wireless communication circuitry, battery, etc., while section  100 B may be a removable eartip formed of a soft compliant material, for example, medical grade silicone. 
     Examples of earbuds  100  disclosed herein may have cross-sections similar to that illustrated in  FIG. 2 d   . In the example illustrated in  FIG. 2 d    an outer leg  30  may extend from the body of the earbud, similar to concha portion  120  in  FIGS. 1 a  and 1 b    to retain the earbud in the ear of a user. A sealing structure  34  is provided to engage the entrance to the user&#39;s ear canal and defines an output aperture  52 . An entrance cavity  69  to an acoustic nozzle  57  having an interior volume  58  may be provided proximal to an acoustic driver  50 . Driver  50  is enclosed in a driver cavity  65  including a front cavity  63  having a first volume and a back cavity  67  having a second volume. An entrance cavity  69  may be formed in front of driver cavity  63  that transitions to an entrance aperture  51  of the nozzle  57 . In the implementation shown in  FIG. 2 d   , the output aperture  55  of nozzle  57  is significantly larger than the entrance aperture  51 . A first acoustic mesh  54  is provided at the entrance aperture  51  of the acoustic nozzle proximate the acoustic driver  50 , and a second acoustic mesh  56  is provided at the output aperture of the acoustic nozzle  57  distal from acoustic driver  50   
       FIGS. 3 a  and 3 b    show partially cut-away views of two different variants of an earbud  100  including sensor systems for determining if the earbud  100  is inserted into the ear of a user. It is to be understood that the form factor illustrated in  FIGS. 3 a  and 3 b    is not limiting, and earbud  100  may alternatively have any of the form factors illustrated in  FIGS. 1 a -2 e    or other form factors known in the art. The sensor systems may include at least one conductive trace  112  disposed on a portion of the earbud  100 , for example, the outside of the canal portion  110 . As illustrated in  FIG. 3 c   , the conductive traces  112  may extend at least partially or substantially wholly about a periphery of the outer surface of the canal portion  110 . Connective traces  114  provide electrical communication between the conductive traces  112  and control/monitor circuitry  180  of the earbud  100 . The conductive traces  112  may have widths of about 10 mils (0.254 mm), thicknesses of between about 1 mil (0.0254 mm) and 10 mils, and may be separated by about 10 mils, although these dimensions are non-limiting examples. The connective traces  114  may have similar dimensions as the conductive traces  112 . The conductive traces  112  and/or connective traces  114  may be formed of, for example, metal film or other conductive material and may be deposited on the earbud  100  using methods known in the art, for example, using methods similar to those for depositing conductive traces on printed circuit boards. 
     Conductive traces  112  that are closer to the concha portion  120  of the earbud  100  than the aperture  118  of the canal portion  110  may extend about the periphery of the canal portion  110  to a lesser degree than conductive traces  112  located closer to the aperture  118  of the canal portion  110  to allow room for the connective traces  114  associated with each individual conductive trace  112  to extend along a length of the canal portion  110 . A conductive trace  112  closest to the aperture  118  of the canal portion  110  among all of the conductive traces  112  may extend completely about the periphery of the canal portion  110 . Alternatively or additionally, insulating material, for example, a thin film of insulting plastic  111  may be provided over the conductive traces  112  and/or between connective traces  114  to prevent short circuits between the conductive traces  112  and/or connective traces  114  or to provide for the connective traces  114  to overlap so that the conductive traces  112  may each extend substantially or completely about the periphery of the canal portion  110  of the earbud  100 . 
     As described more fully below, the control/monitor circuitry  180  of the earbud  100  is configured to measure capacitance between different pairs of conductive traces  112  or between at least one conductive trace  112  and ground to determine if the earbud is inserted properly into the ear of a user and/or provides an acceptable fit and seal in the ear of the user. In other examples, one or more internal conductive traces or a conductive coating  132 , illustrated in  FIGS. 3 b  and 3 d   , may be disposed within at least a portion of the canal portion  110  of the earbud  100 , for example, on an internal surface of the canal portion  110  of the earbud  100 . In implementations in which such internal conductive traces or conductive coating  132  are present the control or monitor circuitry  180  of the earbud  100  may additionally or alternatively be configured to measure capacitance between at least one or different conductive traces  112  and the internal conductive traces or conductive coating  132  to determine if the earbud is inserted properly into the ear of a user and/or provides a good fit and seal in the ear of the user. In a further example illustrated in  FIG. 3 e   , the conductive traces  112  may be combined with the connective traces  114  and may extend along the outside (and/or the inside) of canal portion  110  substantially parallel with an axis A of the canal portion  110 . The skilled artisan will recognize that other configurations and arrangements of the conductive traces  112  and/or connective traces  114  may be implemented in other examples. For example, the conductive traces  112  and/or connective traces  114  may extend helically around or inside the canal portion  110  of the earbud  100 . The number of conductive traces  112  and connective traces  114  illustrated is not intended to be limiting and other examples of earbuds may include fewer or greater number of conductive traces  112  and/or connective traces  114  than illustrated. 
     In another implementation, illustrated in  FIG. 3 f   , a canal portion  110 A of the earbud  100  may be formed from a plurality of stacked washers  117 . The bodies of the washers  117  may be formed of a non-conducive material, for example, a type of plastic commonly used to form the bodies or canal portions of earbuds. Conductive material  119 , for example, a metal film disposed on or within faces of the washers  117  may perform the function of the conductive traces  112  described with reference to the other examples disclosed herein. Connective traces  114  may provide electrical connection between the different layers of conductive material  119  and the monitor or control circuitry of the earbud similar to how the connective traces  114  provide electrical connection to the circuitry  180  as illustrated in, for example,  FIGS. 3 a    and  3   c.    
     In some implementations, one or more pairs of conductive traces  112  (which may be referred to as dummy or redundant conductive traces) may be utilized to measure a baseline capacitance against which the capacitance between other conductive traces  112  or between at least one conductive trace  112  and ground (and/or between at least one conductive trace  112  and internal conductive traces or conductive coating  132 ) may be compared to obtain capacitance measurements used to determine if the earbud is inserted properly into the ear of a user and/or provides an acceptable fit and seal in the ear of the user. This baseline capacitance may change based on changes that occur to the ear of the user, for example, after exercise when the blood vessels of the ear may be more open and the inside of the ear may include sweat or during cold weather during which the blood vessels in the ear may contract. The baseline capacitance may also change if a user switches between different types of removable eartips on the canal portion of the earbud  100 . Other changes in the physical condition of a user can also bring about minor alterations in the dimensions and/or shape of the ear canal that may alter a baseline capacitance of between conductive traces  112 . The capacitance between the active (non-dummy or redundant) conductive traces  112  or between at least one conductive trace  112  and ground (or between at least one conductive trace  112  and internal conductive traces or conductive coating  132 ) may be compared against the baseline capacitance so that changes in the baseline capacitance do not cause the monitoring circuitry  180  of the earbud to derive incorrect conclusions regarding the degree of insertion or fit of the earbud in the ear of the user based on uncompensated capacitance measurements between the active conductive traces  112  or between at least one conductive trace  112  and ground. In some examples, the dummy or redundant conductive traces  112  are dedicated to providing baseline capacitive measurements, but in other examples, control circuitry of the earbud may periodically switch the functionality of the dummy or redundant conductive traces  112  from providing baseline capacitance measurements to providing capacitive measurements used to determine the degree of insertion or fit of the earbud in the ear of the user. 
     The eartips of the earbuds  100  illustrated in  FIGS. 3 a  and 3 b    are represented by elements  150 . Alternate examples of eartips, which may be removable ear tips that may be used with examples of earbuds disclosed herein, are illustrated in  FIGS. 4 a  and 4 b   , indicated generally at  101 . These ear tips  101  have a configuration that includes a body  102  that rests in at least a part of the concha, a retaining leg  103  that rests against and applies pressure to the antihelix, and an outlet  104  that fits within at least an entrance in the ear canal. The ear tip  101  illustrated in  FIG. 4 b    further includes a flexible flap  106  around the outlet. The construction and configuration of the removable ear tips  101  illustrated in  FIGS. 4 a  and 4 b    are described in further detail in commonly owned U.S. Pat. Nos. 8,311,253 and 8,737,669, which are incorporated by reference in their entirety herein. 
     Both variants of the earbud  100  illustrated in  FIGS. 3 a  and 3 b    may incorporate circuitry  180  and an acoustic driver  190  that is electrically coupled to the circuitry  180 . Within the canal portion  110 , a channel  116  is formed that extends from the aperture  118  through to an interior portion  125  of the concha portion  120 . Within the concha portion  120 , the interior portion  125  is separated by a wall structure and the acoustic driver  190  from another interior portion  126  in which the circuitry  180  is depicted as being disposed (though it should be noted that the circuitry  180  may be disposed in any of a variety of locations either within the casing of the earbud  100 , or externally thereof). The earbuds  100  further include a battery  185  to power the various components and wireless communication circuitry built into the circuitry  180  or a separate circuit element (though this may also be located in a housing separate from earbud  100 ). The earbud  100  may also include a microphone  170  that is acoustically coupled to the channel  116  and/or the interior portion  125  and electrically coupled to the circuitry  180  for providing two-way communications through the earbud  100  or feedback-based ANR. Optionally, the earbud  100  may be activated or deactivated with a manually operable power switch  105 . 
     Both of the variants of  FIGS. 3 a  and 3 b    are depicted as having an aperture  128  formed between the interior portion  126  and the environment external to a user&#39;s ear. One or more of the apertures  128  may serve as acoustic ports to tune the frequency response of the acoustic driver  190  and/or may serve to enable equalization of air pressure between the ear canal and the external environment. The apertures  128  may have dimensions and/or other physical characteristics selected to acoustically couple portions within the casing of the earbud  100  to each other and/or to the external environment within a selected range of frequencies. Further, one or more damping elements (not shown), for example, a screen or foam insert, may be disposed within one or more of the apertures  128  to cooperate with characteristics of the acoustic driver  190  to alter frequency response. 
     Additionally or alternatively, one or more of the apertures  128  may be formed in the concha portion  120  (and/or in other portions of the casing) to provide a controlled acoustic leak between the ear canal and the external environmental for purposes of controlling the effects of variations in fit that may develop over time. As will be recognized by those skilled in the art, variations in the health or other aspects of the physical condition of a user can bring about minor alterations in the dimensions and/or shape of the ear canal over time such that the quality of the seal able to be formed with each insertion of the earbud  100  into the ear over time may change. Thus, in some implementations, the dimensions and/or other characteristics of one or more apertures  128  formed in the casing may be selected to aid in mitigating the effects of a slightly degraded quality of seal by providing a pre-existing leak of controlled characteristics that mitigates the acoustic effects of other leaks developing in the future in the seal between the casing of the earbud  100  and portions of the ear. For example, the dimensions of one or more apertures  128  may be selected to be large enough to provide a far greater coupling between the ear canal and the external environment than any other coupling through a leak in the seal that may develop at a later time. 
     The conductive traces  112  and/or internal conductive traces or conductive coating  132  may be electrically coupled to the circuitry  180 . Various of the conductive traces  112  and/or internal conductive traces or conductive coating  132  may receive drive signals from the circuitry  180 . Measurements of capacitance between pairs of conductive traces  112  or between at least one conductive trace  112  and ground (and/or internal conductive traces or conductive coating  132 ) may be obtained from electrical measurements (e.g., voltage potential) taken from undriven conductive traces  112  by the circuitry  180 . In various implementations, either a dedicated controller, or part of a System on Chip integrated circuit, may be used to determine the capacitance between pairs of conductive traces  112  (and/or internal conductive traces or conductive coating  132 ). One example of a controller that may be used to determine the capacitance between pairs of conductive traces  112  (and/or internal conductive traces or conductive coating  132 ) to determine the relative position of the sensing electrodes with respect to the ear canal is a Cypress PSoC 4000S series controller with built-in capacitance sensing. 
     When the earbud  100  is not inserted into the ear of a user, capacitance between different pairs of conductive traces  112  or between at least one conductive trace  112  and ground (and/or internal conductive traces or conductive coating  132 ) may be at a first level defined by factors such as geometry of the conductive traces and the dielectric constant of the medium surrounding the conductive traces, e.g., air. When the earbud  100  is inserted into the ear of a user, the dielectric constant of the flesh of the ear canal causes the capacitance between pairs of conductive traces  112  or between at least one conductive trace  112  and ground to change, for example, to increase, thus providing an indication that the earbud  100  is inserted into the ear of the user. As a user inserts the earbud  100  into the ear of the user capacitance between conductive traces  112  closer to the aperture  118  end of the canal portion  110  change before capacitance between conductive traces  112  closer to the concha  120  end of the canal portion  110  change. The circuitry  180  may detect this pattern of capacitance changes to determine that the earbud  100  is being inserted into the ear of the user. The extent to which the capacitance between different pairs of conductive traces  112  changes may provide an indication of the degree of insertion of the earbud into the ear of the user. In some examples, the earbud may provide the user with an indication of the depth of insertion of the earbud in the ear of the user, for example, by the circuitry  180  causing the acoustic driver  190  to emit sound pulses or tones that vary depending on a degree of insertion of the earbud into the ear of the user. In other examples, the earbud could emit a signal when the insertion reaches an optimal point, for example, a point at which the earbud is fully inserted into the ear of the user. As the earbud is removed from the ear of the user, the opposite pattern may be observed—for example, capacitance between conductive traces  112  closer to the concha  120  end of the canal portion  110  change before capacitance between conductive traces  112  closer to the aperture  118  end of the canal portion  110  change. The circuitry  180  may detect this pattern of capacitance changes to determine that the earbud  100  is being removed from the ear of the user and in some examples may provide an indication of same to the user, for example, by providing an audio tone or pattern through the acoustic driver  190  that varies depending on a degree of insertion of the earbud into the ear of the user. Indications may also be provided via a user interface of an application running on a device connected to the earbud wirelessly. In some examples, the earbud may automatically shut down responsive to detecting a pattern of capacitance changes indicative of the earbud having been removed from the ear of the user. 
     In some implementations, the circuitry  180  may be configured to differentiate between a pattern of capacitance changes between pairs of conductive traces  112  or between at least one conductive trace  112  and ground that would be observed when inserting or removing the earbud  100  from the ear of the user and a pattern of capacitance changes between pairs of conductive traces  112  or between at least one conductive trace  112  and ground that would be observed when a user is manually handling the earbud  100 . For example, as described above the capacitance between pairs of conductive traces  112  or between at least one conductive trace  112  and ground may change in a predictable pattern as the earbud  100  is inserted or removed from the ear of the user. A different pattern of observed changes in capacitance between pairs of conductive traces  112  or between at least one conductive trace  112  and ground may be recognized by the circuitry  180  as being indicative of manual handling of the earbud  100  and may be ignored with regard to determining a degree of insertion of the earbud  100  in the ear of the user. 
     In some examples, once the earbud  100  has been fully inserted into the ear of the user, the measured capacitance between different conductive traces or between at least one conductive trace and ground may provide an indication of a degree of fit of the earbud in the ear of the user. For example, if the capacitance between certain pairs of conductive traces  112  or between at least one conductive trace  112  and ground is different, e.g., less than would be expected if a proper fit were achieved, the circuitry may determine that the earbud is not properly inserted and may provide an indication of same to the user, for example, by emitting a tone or other sound pattern, or via a user interface of an application running on a device connected to the earbud wirelessly. Such a tone, sound pattern, or user interface output may be considered instructions from the circuitry to the user to reposition the earbud  100  into a more proper position in the ear of the user. If the measured capacitance levels are consistent with the earbud  100  being properly inserted into the ear of the user, the circuitry  180  may cause the earbud to emit a tone or beep or provide another indication of proper insertion to the user. In both instances, the earbud could additionally or alternatively emit an audio message, such as “the ear bud is not fully inserted” or “the ear bud is properly inserted.” In another example, if the measured capacitance between different pairs of conductive traces  112  or between at least one conductive trace  112  and ground is not steady, this may indicate that the earbud  100  is loose in the ear of the user. The circuitry may provide an indication to the user that the earbud  100  is loose so that the user might, for example, reinsert the earbud or try a different removable eartip that may provide a better degree of fit in the ear of the user. 
       FIG. 5  provides a block diagram of a controller  200  with which insertion of an earbud as disclosed herein within an ear of a user may be detected. The controller  200  may be included within the body of an earbud, for example, within circuitry  180 . The controller may be formed on a circuit board  300 . Each earbud in a pair of earbuds may include a controller  200 , or a single controller  200  may control operation of both earbuds in a pair and may communicate via a wired or wireless connection between the two earbuds in the pair. 
     The controller  200  incorporates a voltage control  252  to controllably provide a driving voltage to one or more conductive traces  112  disposed on or in the canal portion  110  of an earbud  100 . The controller  200  also incorporates a user interface  230  which may wirelessly communicate with an external system, for example, a cell phone or computer, for receiving programming or providing recorded information, a storage  220  in which is stored a control routine  225  and control data  226 , and a processing device  210  coupled to the storage  220  to access and execute a sequence of instructions of the control routine  225 . The processing device  210  is also coupled to the voltage control  252  to operate the voltage control  252  to effect the application of a controlled voltage to the one or more of the conductive traces  112  and is further coupled to the receiver interface  255  which receives signals from one or more receiving conductive traces  112  disposed on or in the canal portion of an earbud  100 . The controller  200  also incorporates at least an earpiece interface  290  to enable coupling of the controller  200  to the built-in microphone  170  and the acoustic driver  190  to be driven to acoustically output various test sounds that may be used to help calibrate the determination of insertion of earbuds in the ear of a user by the controller  200 . In some implementations separate voltage controllers  252  are provided for each driven conductive trace  112  in an earbud or pair of earbuds, and in other implementations, a single voltage controller  252  is used with each driven conductive trace in an earbud or pair of earbuds. Similarly, in some implementations separate receiver interfaces  255  are provided for each receiving conductive trace  112  in an earbud or pair of earbuds, and in other implementations, a single receiver interface  255  is used with each receiving conductive trace  112  in an earbud or pair of earbuds. 
     An implementation of a method of operating an earbud  100  with a capacitive earbud insertion sensor as shown in  FIG. 3 a    is illustrated in the flowchart of  FIG. 6 , indicated generally at  600 . In act  605  a user activates the earbud. The user may activate the earbud by pressing a power switch. Additionally or alternatively, the earbud may include an accelerometer, for example, a microelectromechanical accelerometer built into the circuitry of the earbud that detects movement of the earbud and may activate the earbud when a user picks up the earbud. Further, the earbud may activate when the capacitive sensor detects changes in capacitance between conductive traces or between at least one conductive trace and ground indicative of manual handling of the earbud. Activation of the earbud may cause a timer to begin counting down (acts  610 ,  615 ). Upon expiration of the timer (act  615 ) the earbud controller may determine whether a signal from driven capacitive traces being received at receiving conductive traces or a capacitance between at least one conductive trace and ground is consistent with the at least one conductive trace or conductive traces being located in the ear canal of the user to determine if the earbud is inserted into the ear of the user (act  620 ). In some embodiments, the earbud controller determines that the earbud is inserted into the ear of the user if a signal from the receiving conductive traces or between at least one conductive trace and ground was indicative of the capacitance between the driven and receiving conductive traces or between at least one conductive trace and ground having increased over a period of time from a first time to a second time. A threshold amount of capacitance change, for example, at least about 90% or at least about 75% change in capacitance as compared to an expected change in capacitance may be set for determining if the earbud is inserted into the ear of the user. 
     If the earbud was determined to be properly inserted in the ear of the user in decision act  620 , the earbud may optionally provide an indication of proper insertion being detected, for example, by emitting a click or a tone (act  625 ) and the earbud may begin to render audio content (act  630 ). In some embodiments, the earbud need not wait for the timer to expire but may continuously check for proper insertion of the earbud after the earbud is activated and may provide an indication of proper insertion being detected and begin to render audio any time prior to expiration of the timer. 
     If the earbud was not determined to be properly inserted in the ear of the user in decision act  620  or prior to expiration of the timer, the earbud may optionally provide an indication of improper insertion (act  635 ), for example, a pattern of clicks or a tone different from that used to provide an indication of proper insertion of the earbud in the ear of the user. The earbud may then begin and await expiration of a second timer (acts  640 ,  645 ) and if the earbud is not determined to be properly inserted in the ear of the user prior to or at the time of expiration of the second timer (act  650 ), the earbud controller may deactivate the earbud (act  655 ). If, however, in decision act  650  the earbud controller determines that the earbud is properly inserted into the ear of the user it may optionally provide an indication of proper insertion being detected, for example, by emitting a click or a tone (act  625 ) and the earbud may begin to render audio content (act  630 ). 
     Periodically, for example, at a rate of between about 1 second, 5 seconds, 10 seconds, 30 seconds, 1 minute or 5 minutes, the earbud may recheck if it is still inserted into the ear of the user (act  660 ). In addition, or alternatively, upon detection of an event, for example, detecting movement of the earbud via an accelerometer built into the earbud, the earbud may recheck if it is still inserted into the ear of the user (act  660 ). If the earbud is still inserted into the ear of the user the earbud may continue rendering audio content. If in decision act  660  the earbud controller determines that the earbud is not still inserted into the ear of the user, for example, by determining that the capacitance between one or more pairs of conductive traces decreased to a level inconsistent with the earbud being disposed in the ear canal of the user, the method may proceed to act  635  and the earbud may provide the indication of improper insertion and be deactivated if not determined to be inserted into the ear of the user prior to expiration of the second timer (acts  640 - 655 ). 
     It is to be understood the method illustrated in  FIG. 6  may also be applicable to earbuds having a conductive trace or conductive coating internal to the canal portion of the earbud, for example, as in the earbud illustrated in  FIG. 3 b   . The method illustrated in  FIG. 6  may also be applicable to detecting proper insertion of both earbuds in a pair of earbuds. For example, in decision acts  620 ,  650 , and  660 , the earbud controller may make a determination if one or both of the earbuds in a pair of earbuds are properly inserted into the ear of a user, may cause audio content to be rendered through one or both earbuds in act  630 , and may deactivate one or both earbuds in the pair in act  655 . 
     Having thus described several aspects of at least one implementation, it is to be appreciated various alterations, modifications, and improvements will readily occur to those skilled in the art. Such alterations, modifications, and improvements are intended to be part of this disclosure, and are intended to be within the spirit and scope of the disclosure. The acts of methods disclosed herein may be performed in alternate orders than illustrated, and one or more acts may be omitted, substituted, or added. One or more features of any one example disclosed herein may be combined with or substituted for one or more features of any other example disclosed. Accordingly, the foregoing description and drawings are by way of example only. 
     The phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. As used herein, the term “plurality” refers to two or more items or components. As used herein, dimensions which are described as being “substantially similar” should be considered to be within about 25% of one another. The terms “comprising,” “including,” “carrying,” “having,” “containing,” and “involving,” whether in the written description or the claims and the like, are open-ended terms, i.e., to mean “including but not limited to.” Thus, the use of such terms is meant to encompass the items listed thereafter, and equivalents thereof, as well as additional items. Only the transitional phrases “consisting of” and “consisting essentially of,” are closed or semi-closed transitional phrases, respectively, with respect to the claims. Use of ordinal terms such as “first,” “second,” “third,” and the like in the claims to modify a claim element does not by itself connote any priority, precedence, or order of one claim element over another or the temporal order in which acts of a method are performed, but are used merely as labels to distinguish one claim element having a certain name from another element having a same name (but for use of the ordinal term) to distinguish the claim elements.