Patent Publication Number: US-11665463-B2

Title: Wearable audio device with modular battery and electronics

Description:
PRIORITY CLAIM 
     This application claims priority to U.S. Provisional Patent Application No. 62/935,742, filed on Nov. 15, 2019, which is hereby incorporated by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     This disclosure generally relates to wearable audio devices. More particularly, the disclosure relates to wearable audio devices with modular battery and communications units. 
     BACKGROUND 
     Consumers continue to demand ever-smaller wearable audio devices. However, as these devices reduce in size, many technical challenges arise. For example, as wearable audio devices such as wireless headphones, earphones (e.g., earbuds) and other wireless body-worn audio devices reduce in size, battery life and wireless performance are impacted. These tradeoffs can present challenges for device designers. 
     SUMMARY 
     All examples and features mentioned below can be combined in any technically possible way. 
     Various implementations of the disclosure include wearable audio devices and related systems. Particular implementations of the disclosure include wearable audio devices with modular battery components and related storage and/or charging systems. 
     In particular aspects, a wearable audio device includes: a base having: an acoustic transducer; a controller coupled with the acoustic transducer; and terminals for connecting a power source; and a first cap including: an antenna; and a battery including terminals for connecting with the terminals in the base, where the first cap is removably coupled to the base. 
     In other particular aspects, a system includes: a wearable audio device including: a base having: an acoustic transducer; a controller coupled with the acoustic transducer; and terminals for connecting a power source; a first cap including: an antenna; and a battery having terminals for connecting with the terminals in the base, where the first cap is removably coupled to the base; at least one additional cap including: an antenna; and a battery having terminals for connecting with the terminals in the base, where the at least one additional cap is decoupled from the base, and where the base is configured to couple with only one of the first cap or one of the at least one additional cap at a time; and a storage case including at least one slot for the accommodating at least one of: the base and the first cap when coupled to one another, or the base and one of the at least one additional cap when coupled to one another. 
     Implementations may include one of the following features, or any combination thereof. 
     In certain aspects, the wearable audio device further includes: at least one additional cap including: an antenna; and a battery having terminals for connecting with the terminals in the base, where the at least one additional cap is decoupled from the base, and where the base is configured to couple with only one of the first cap or one of the at least one additional cap at a time. 
     In some cases, the battery in the at least one additional cap has an approximately equal capacity as the battery in the first cap, or a greater capacity than the battery in the first cap. 
     In particular implementations, the first cap and the at least one additional cap have distinct visual characteristics. 
     In certain cases, the first cap and the additional cap(s) are sized to fit in a storage case with the base, where the storage case includes: a first set of slots for accommodating the base while coupled with the first cap or the additional cap; and a second set of slots for accommodating the other of the first cap or the additional cap not coupled with the base. 
     In particular aspects, the at least one additional cap provides additional power to the wearable audio device while the first cap is not in use. 
     In certain implementations, the antenna in each of the first cap and the additional cap is located proximate an outermost surface of the first cap and the additional cap such that communications signals to and from the antenna are substantially unobstructed by the battery. 
     In some cases, the base and the first cap are removably coupled by at least one mating feature in addition to connections between the terminals in the base and the terminals in the first cap. 
     In particular aspects, the mating feature(s) include: a magnet, a male/female coupler, a force-fit coupler, a threaded coupler and/or a slot-loaded coupler. 
     In some implementations, the wearable audio device includes a set of earbuds, and each earbud includes the base and the first cap. 
     In certain cases, the base substantially envelops the first cap such that when coupled to form each earbud, an outer surface of the first cap extends beyond a distal end of the base by less than approximately 10-20 percent of a length of the base as measured from a proximal end of the base. 
     In particular implementations, the set of earbuds include a hearing assistance audio device, and the base in at least one of the earbuds includes a light for differentiating a left earbud from a right earbud in the set of earbuds. 
     In some aspects, the light is further configured to indicate a remaining life in the battery. 
     In particular cases, the first cap further includes additional electronics. 
     In certain implementations, the base and the first cap each include a set of electrical contacts for transmitting data between the additional electronics and the controller. 
     In some cases, the additional electronics include at least one of: a user interface, an environmental sensor, a motion/orientation sensor or a communications module. 
     In particular aspects, the user interface includes a tactile interface, the environmental sensor includes at least one of: a pressure sensor, a humidity sensor or an air quality sensor, the motion/orientation sensor includes at least one of: an inertial measurement unit or an optical sensor, and the communications module includes at least one of: a Bluetooth module, a Bluetooth Low Energy (BLE) module, a near-field magnetic induction (NFMI) module or a cellular module. 
     In certain implementations, the storage case includes a charging case having a power source for charging: the base coupled with the first cap or the additional cap; and the other of the first cap or the additional cap that is decoupled from the base. 
     In particular aspects, the wearable audio device includes a set of earbuds, and each earbud includes the base and the first cap, where the storage case includes a charging case and the at least one slot includes two slots for charging only the base and a coupled one of the first cap or an additional cap for each earbud. 
     In certain cases, the system further includes a supplemental charging case that is removably coupled with the charging case, the supplemental charging case having: at least one additional slot for charging a decoupled one of the first cap or the at least one additional cap; and an additional power storage device. 
     In some implementations, the storage case includes a tool for at least one of coupling or decoupling the first cap or the at least one additional cap with the base. 
     Two or more features described in this disclosure, including those described in this summary section, may be combined to form implementations not specifically described herein. 
     The details of one or more implementations are set forth in the accompanying drawings and the description below. Other features, objects and advantages will be apparent from the description and drawings, and from the claims. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG.  1    shows a schematic depiction of an audio device according to various implementations. 
         FIG.  2    shows a break-away view of portions of the audio device of  FIG.  1   . 
         FIG.  3    shows a schematic depiction of an additional audio device according to various implementations. 
         FIG.  4    is a system diagram illustrating electronics in components within an audio device according to various implementations. 
         FIG.  5    is a schematic perspective view of an audio device according to various implementations. 
         FIG.  6    shows a first polar plot of the radiation pattern from an antenna on an audio device according to various implementations. 
         FIG.  7    shows a second polar plot of the radiation pattern from the antenna on an audio device according to various implementations. 
         FIG.  8    shows distinct perspective views of a cap for an audio device according to various implementations. 
         FIG.  9    shows distinct caps for an audio device according to various implementations. 
         FIG.  10    shows a system including a storage case and an audio device according to various implementations. 
         FIG.  11    shows a system including a storage case and an audio device according to various additional implementations. 
     
    
    
     It is noted that the drawings of the various implementations are not necessarily to scale. The drawings are intended to depict only typical aspects of the disclosure, and therefore should not be considered as limiting the scope of the invention. In the drawings, like numbering represents like elements between the drawings. 
     DETAILED DESCRIPTION 
     As noted herein, various aspects of the disclosure generally relate to wearable audio devices. More particularly, the disclosure relates to wearable audio devices with modular battery and communications units. 
     Commonly labeled components in the FIGURES are considered to be substantially equivalent components for the purposes of illustration, and redundant discussion of those components is omitted for clarity. 
     Aspects and implementations disclosed herein may be applicable to a wide variety of audio devices that can benefit from modular battery and communications units. Implementations disclosed herein can be applicable to wearable audio devices in various form factors, such as headphones (whether on or off ear), headsets, watches, eyeglasses, neck-worn speakers, shoulder-worn speakers, body-worn speakers, etc. Unless specified otherwise, the term wearable audio device, as used in this document, includes headphones and various other types of personal audio devices such as head, shoulder or body-worn acoustic devices that include one or more acoustic drivers to produce sound. Some particular aspects disclosed may be applicable to personal (wearable) audio devices such as in-ear headphones (also referred to as earbuds), eyeglasses or other head-mounted audio devices. Earbuds are described with particular detail in portions of the disclosure. 
     While described by way of example, wearable audio devices such as in-ear headphones (e.g., earbuds), audio accessories or clothing (e.g., audio hats, audio visors, audio jewelry, neck-worn speakers or audio eyeglasses (also referred to as eyeglass headphones) herein, the wearable audio devices disclosed herein can include additional features and capabilities. That is, the wearable audio devices described according to various implementations can include features found in one or more other wearable electronic devices, such as smart glasses, smart watches, etc. These wearable audio devices can include additional hardware components, such as one or more cameras, location tracking devices, microphones, etc., and may be capable of voice recognition, visual recognition, and other smart device functions. Additional capabilities of the wearable audio devices are described, for example, in U.S. patent application Ser. No. 16/179,205 (Spatialized Virtual Personal Assistant, filed on Nov. 2, 2018), which is herein incorporated by reference in its entirety. The description of wearable audio devices included herein is not intended to exclude these additional capabilities in such a device. 
     Various particular implementations include systems that can include wearable audio devices and related storage and/or charging cases. In certain implementations, a wearable audio device includes a base that has an acoustic transducer, a controller, and terminals for connecting a power source. The wearable audio device also has a cap that includes an antenna and a battery with terminals for connecting with the terminals in the base. The cap is removably coupled to the base, such that the cap can be replaced with an additional, removable cap. In various implementations, a system includes a storage case that has one or more slots for accommodating the base and removable cap(s). The storage case can be configured for charging the cap(s) in various implementations. 
       FIGS.  1  and  2    are schematic perspective and break-away perspective views, respectively, of a wearable audio device  10  according to various implementations. In this example depiction, the wearable audio device  10  includes a set of (e.g., two) earbuds  15 . In other implementations, the wearable audio device  10  can include any of the various wearable audio devices described herein, e.g., headphones, audio glasses, etc. For example,  FIG.  3    illustrates an additional form factor for the audio device  10 , including audio eyeglasses  25 . Common components in the earbuds  15  in  FIGS.  1  and  2   , and the audio eyeglasses  25  in  FIG.  3    are described collectively. While reference is made to the earbuds in  FIGS.  1  and  2    in many circumstances, those descriptions can equally apply to similar components in the audio eyeglasses  25  in  FIG.  3   . 
     With reference to  FIGS.  1 - 3   , the wearable audio device  10  is shown including a base  20 , and a first cap (or simply, cap)  30  for removably coupling with the base  20 .  FIG.  2    and  FIG.  3    each depicts the cap  30  removed from the base  20 . As noted herein, the cap  30  is capable of being decoupled from the base  20 , and subsequently re-coupled or replaced with a distinct cap (e.g., a similar replacement cap or a distinct cap). 
     In certain implementations, the base  20  includes a set of electronics  40 , and the cap  30  includes a distinct set of electronics  50 . That is, electronics  40  in the base  20  are physically separated from electronics  50  in the cap  30 . A schematic depiction of the electronics  40 ,  50  is included in  FIG.  4   . As shown, the electronics  40  in the base  20  can include at least one acoustic transducer  60 , and a controller  70  coupled with the acoustic transducer(s)  60 . The base  20  can also include terminals  80  for connecting the base  20  with a power source. The acoustic transducer  60  is configured to provide an audio output to the user, and may be configured for either closed-ear (e.g., in-ear or on-hear) or open-ear (or, near-ear) output. 
     The controller  70  can include various audio control components as well as device control components, e.g., hardware and/or software for performing functions described herein. For example, the controller  70  can include a processor (e.g., including a logic engine) to execute instructions for controlling device functions (e.g., to turn on or off functions in device  10 , to start or stop audio playback, etc.), and may handle other device operations. In some cases, a memory is coupled with the processor to store the instructions. The memory at the device(s) can include, for example, flash memory and/or non-volatile random access memory (NVRAM). In some implementations, instructions (e.g., software such as a device detection application) are stored in an information carrier. The instructions, when executed by one or more processing devices, perform one or more processes to control device  10  functions. The instructions can also be stored by one or more storage devices, such as one or more (e.g. non-transitory) computer- or machine-readable mediums (for example, the memory, or memory on the processor). As described herein, the memory can include instructions, or the processor can otherwise access instructions for detecting connection with the cap  30  and taking a prescribed action according to various particular implementations. It is understood that portions of the memory (e.g., instructions) can also be stored in a remote location or in a distributed location, and can be fetched or otherwise obtained by the processor (e.g., via any communications protocol described herein) for execution. 
     In various implementations, the controller  70  also includes a radio and other audio control components. For example, the radio can include a radio-frequency (RF) transmitter for supporting wireless communication with external equipment. To support interactions with external equipment, the controller  70  can further include storage and processing circuitry used in implementing communications protocols. Communications protocols that may be implemented using storage and processing circuitry include wireless local area network protocols (e.g., IEEE 802.11 protocols—sometimes referred to as WiFi® and WiGig), protocols for other short-range wireless communications links such as the Bluetooth® protocol, cellular telephone protocols, etc. 
     The (first) cap  30  is shown having an antenna  90 , and a battery  100  with terminals  110  for connecting with the terminals  80  in the base  20 . The antenna  90  is configured to transmit and receive wireless signals. In certain implementations, the electronics  40  in the base  20  and the electronics  50  in the cap  30  are configured to communicate with a communications gateway  120 , e.g., a smartphone, smart watch, or other audio playback device. As noted herein, the antenna  90  can enable certain communications between the communications gateway  120  and the audio device  10 , e.g., communication with the controller  70  in the base  20 . 
     In certain cases, the antenna  90  includes one or more metal traces (e.g., primary antenna trace and a ground trace) connected with a printed circuit. The antenna  90  can be configured to communicate wirelessly with external electronic equipment over a wireless communications link. The wireless communications link may be a cellular telephone link (e.g., a wireless link at frequencies of 700 MHz to 2700 MHz or other suitable cellular telephone frequencies), may be a wireless local area network link operating at 2.4 GHz, 5 GHz, or other suitable wireless local area network frequencies, may be a Bluetooth® link operating at 2.4 GHz, may involve millimeter wave communications, may involve near-field communications, or may involve wireless communications in other communications bands. Configurations in which device  10  operates at 2.4 GHz to support short-range communications such as Bluetooth® communications may sometimes be described herein as an example. 
     The antenna  90  can be formed using any suitable antenna type. For example, antenna  90  may be an antenna with a resonating element that is formed from a loop antenna structure, a patch antenna structure, an inverted-F antenna structure, a slot antenna structure, a planar inverted-F antenna structure, a helical antenna structure, a monopole, a dipole, hybrids of these designs, etc. If desired, antenna  90  may include tunable circuitry and controller  70  may be used to select a preferred setting for the tunable circuitry to tune antenna  90  when the cap  30  is connected with the base  20 . Antenna adjustments may be made to tune antenna  90  to perform in a desired frequency range or to otherwise optimize antenna performance. Sensors may be incorporated into antenna  90  or elsewhere in device  10  to gather sensor data in real time that is used in adjusting antenna  90 . Antenna  90  may also be implemented using a fixed (non-tunable) configuration. Example configurations of the antenna  90  are further described in U.S. patent application Ser. No. 16/389,240, entitled “Multi-Arm Spiral Antenna for a Wireless Device,” filed on Apr. 19, 2019, which is herein incorporated by reference in its entirety. 
     An example depiction of an antenna  90  over a battery  100  in a cap  30  is illustrated in  FIG.  5   . In this example, the antenna  90  has a plurality of traces  130  proximate to (e.g., on or just below) an outermost surface  140  of the cap  30 . That is, as illustrated in  FIGS.  4  and  5   , the antenna  90  can be located proximate the outermost surface  140  of the cap  30 . In these cases, the antenna  90  is located closer to the outermost surface  140  of the cap  30  than the battery  100 , such that signals to and from the antenna  90  are substantially unobstructed by the battery  100 . That is, when worn by a user, the antenna  90  is located outboard of the battery  100  in order to minimize interference with signals to and from the antenna  90 . 
       FIGS.  6  and  7    are polar plots illustrating the vertical and horizontal polarization patterns, respectively, of the example antenna  90  in  FIG.  5   . Despite the close proximity of the battery  100  to the antenna  90 , the radiation behavior of the antenna  90  is only minimally affected by the presence of the battery  100 . 
       FIG.  8    shows three distinct views of the cap  30  separated from the base  20  ( FIG.  1   ,  FIG.  2   ) in the earbud configuration. Only the cap  30  is illustrated in  FIG.  8   . As shown in  FIGS.  1 - 3  and  8   , the base  20  and the cap  30  include at least one mating feature  150  in addition to connections between the terminals  80  in the base  20  and the terminals  110  in the cap  30 . In various implementations, the base  20  includes a first mating feature  150 A ( FIG.  2   ,  FIG.  3   ), and the cap  30  includes a second, complementary mating feature  150 B ( FIGS.  2 ,  3  and  8   ). The mating features  150  are configured to physically retain the cap  30  on the base  20  when engaged. In certain implementations, the mating feature(s)  150  include at least one of: a magnet, a male/female coupler, a force-fit coupler, a threaded coupler or a slot-loaded coupler. In particular implementations, as illustrated in  FIG.  1    and  FIG.  2   , the audio device  10  has a decoupling feature  160  for separating the cap  30  from the base  20 . In certain implementations, the decoupling feature  160  includes a slot or recess enabling a user to separate the cap  30  from the base  20 , e.g., by inserting a fingernail in the slot or gripping the cap  30 . 
     In particular implementations, as illustrated in  FIG.  1    and  FIG.  2   , the base  20  can substantially envelop the cap  30  such that when coupled to form the audio device  10  (e.g., earbud  15 ), the outer surface  140  of the cap  30  extends beyond a distal end  180  of the base  20  by less than approximately 10-20 percent of a length of the base  20  (as measured from a proximal end  190  of the base  20 ). Additionally, the base  20  can envelop the cap  30  in one or more additional directions that are perpendicular to the length of the base  20 . For example, the base  20  can envelop the cap  30  in such a way that the outer surface  140  of the cap  30  does not extend beyond the outer surface  250  of the base  20  in a direction perpendicular to the length of the base  20 , or only nominally extends beyond the outer surface  250  of the base  20  in those perpendicular directions. In this sense, the cap  30  mates to the existing footprint of the base  20  in these directions that are perpendicular to the length of the base  20 .  FIG.  3    illustrates the audio device  10  in the form of audio eyeglasses  25 , where the cap  30  fits in a slot  195  in the base  20 . Similarly to the earbud form in  FIGS.  1  and  2   , when coupled with the base  20 , the cap  30  extends beyond the outer perimeter of the eyeglass arm  200  by less than approximately 10-20 percent of a thickness of the eyeglass arm  200 . 
     In additional implementations, the audio device  10  is a hearing assistance audio device, such as a hearing aid. In these cases, as illustrated in  FIGS.  1 ,  2  and  4   , the base  20  can include at least one light  210  for differentiating a left earpiece from a right earpiece, e.g., differentiating the left earbud from the right earbud. In certain implementations, one base  20  has a light  210  for indicating that an earpiece is a left or right earpiece. In other implementations, both bases  20  have a light  210  for indicating a difference between left and right earpieces, e.g., with distinct colors for left and right earpieces. In still further implementations, the audio device  10  can include an additional light  210 A for indicating a remaining life in the battery  100 . In these cases, the additional light  210 A can be located on the base  20  in a position that is visible from the outer ear of the user. In some cases, the additional light  210 A is only engaged (e.g., lit) when the remaining life in the battery  100  reaches a threshold (e.g., 20% remaining or below). 
     In certain implementations, the base  20  and/or the cap  30  can include additional electronics  220  ( FIG.  4   ). In various particular cases, the base  20  includes additional electronics  220  such as a user interface (UI), an environmental sensor, a motion/orientation sensor and/or a communications module. According to some examples, all of the additional electronics  220  are contained in the base  20 . In these example implementations, the controller  70  is connected with the additional electronics  220  (e.g., via hard-wired and/or wireless means). Additional electronics  220  are illustrated in phantom as contained within the base  20  to reflect this optional implementation. 
     In still further implementations, the cap  30  contains one or more components in the additional electronics  220  (illustrated in phantom in this optional implementation). That is, the cap  30  that houses the battery  100  and the antenna  90  can also include additional electronics  220  for performing various functions described herein. In the case that the cap  30  includes additional electronics  220 , the base  20  and the cap  30  can include a set of electrical contacts  230 ,  240 , respectively for transmitting data between the additional electronics  220  in the cap  30  and the controller  70  in the base  20 . In various implementations, the electrical contacts  230 ,  240  are located on a same side of each of the base  20  and cap  30  as the terminals  80 ,  110 . That is, the electrical contacts  230  are located on sides of the base  20  and cap  30 , respectively, such that when the cap  30  is mounted to the base  20 , the electrical contacts  230  contact one another and are obstructed from view by the user. 
     In particular implementations, the UI includes a tactile interface such as a capacitive touch interface or other touch-based interface for receiving user commands, e.g., tap, double-tap, tap-and-hold, swipe, etc. In the example depictions in  FIGS.  1 - 3   , the UI can be located along the outer surface  250  of the base  20  that is exposed when the cap  30  is coupled to the base  20 . That is, the UI is located along the outer surface  250  that is accessible to the user&#39;s touch when the cap  30  is coupled to the base  20 . In other cases, where a portion of the UI is located in the cap  30 , the UI can be located along the outermost surface  140  of the cap  30 . 
     In certain cases, the environmental sensor includes a pressure sensor, a humidity sensor and/or an air quality sensor. In various implementations, two or more environmental sensors are combined in the same sensor housing within the additional electronics  220 . In some cases, environmental sensor(s) can be located outboard of the battery  100  when located in the cap  30 . 
     In some cases, the motion/orientation sensor includes an inertial measurement unit (IMU) and/or an optical sensor. In various implementations, the motion/orientation sensor is configured to detect motion of the audio device  10  and/or changes in orientation of the audio device  10  in order to enable device functions. In the case that the motion/orientation sensor includes an IMU, the IMU can include a microelectromechanical system (MEMS) device that combines a multi-axis accelerometer, gyroscope, and/or magnetometer. Example optical sensors can include a camera or light-based sensor. 
     In additional aspects, the communications module includes one or more of: a) a Bluetooth module, a Bluetooth Low Energy (BLE) module, a near-field magnetic induction (NFMI) module or a cellular module. In various implementations, the communications module is configured to communicate with other components in the audio device  10 , e.g., communicate between headphones such as the two earbuds  15  shown in  FIG.  1   . Additionally, or alternatively, the communications module is configured to communicate with other devices, e.g., the communications gateway  120  ( FIG.  4   ). As noted herein, one or more communications modules can be located in the base  20  and/or the cap  30 . In particular examples, a BLE module, Bluetooth module and/or NFMI module can be located in the cap  30  in various configurations. In certain cases, location of communication modules between the base  20  and cap  30  is dictated by the footprint of those modules. 
     In particular cases, as noted herein, one or more additional electronics  220  are located in the cap  30 , and in some cases, the modular configuration of the cap  30  enables distinct caps with distinct sets of additional electronics  220  therein. In certain cases, e.g., where particular additional electronics  220  are located in the cap  30 , the audio device  10  can include one or more additional terminal connections (e.g., such as terminals  80 ,  110 ) and/or one or more additional contacts (e.g., electrical contacts  230 ,  240 ) for accommodating communications protocols such as those described herein. 
     In one example implementation, the environmental sensor is located in the cap  30 , and can be part of an modular configuration for use in areas where environmental sensitivity is high, e.g., areas where air quality is sub-optimal and subject to significant changes. In these cases, the user can connect a version of the cap  30  with additional electronics  220  that include an environmental sensor for use in these areas. In still other cases, the motion/orientation sensor can enable particular device functions such as augmented reality (AR) audio functions, and when located in the cap  30 , can provide a modular configuration where the user can substitute a cap  30  that does not include a motion/orientation sensor for a cap  30  that includes a motion/orientation sensor for enabling AR audio functions. In some cases, the controller  70  in the base  20  is configured to detect the presence of one or more additional electronics  220  in the cap  30  and enable functions in the audio device  10  based upon the detected additional electronics  220 . 
       FIG.  9    is a perspective view of the cap  30  described with reference to  FIGS.  1 ,  2 , and  4   , along with an additional cap  30 A. In various implementations, the additional cap  30 A can include components similarly described with respect to cap  30 , e.g., an antenna  90 , battery  100  and terminals  110  ( FIG.  4   ). In various implementations, the additional cap  30 A is configured to provide power to the audio device  10  while the first cap  30  is not in use, e.g., while the first cap  30  is being stored and/or is recharging. 
     In some cases, the additional cap  30 A can include additional electronics  220  and/or contacts  240  that are described with reference to certain embodiments of the cap  30  ( FIG.  4   ). In other cases, the additional cap  30 A can be substantially identical in type to the first cap  30 , e.g., having an approximately equal battery capacity (where “approximately” is defined as equal +/− a degree of measurement error or nominal variation such as a few percent). In still further implementations, the additional cap  30 A can have distinct visual characteristics from the first cap  30 , e.g., a distinct color or ornamentation. In such cases, a user may wish to install a cap  30 ,  30 A that has desirable and/or distinctive visual characteristics. 
     In certain cases, the additional cap  30 A is configured to couple with the base  20  in the same manner as the first cap  30 , such that only one of the caps  30 ,  30 A can couple to a base  20  at a given time. In particular implementations, the caps  30 ,  30 A are directionally indifferent, such that a cap  30 ,  30 A can be configured to couple with both a left and a right earbud  15  or other headphone (e.g., as shown in  FIG.  1   ). 
     In still other cases, the additional cap  30 A can include a battery  100  that has a distinct capacity from the battery  100  in cap  30  ( FIG.  4   ). In certain cases, the additional cap  30 A has a larger or otherwise higher-capacity battery  100  as compared with the battery  100  in the cap  30 , providing for longer life. In these cases, the larger additional cap  30 A is compatible with the base  20  (e.g., in  FIGS.  1  and  2   ) just as the first cap  20  is compatible with that base  20 . This enables a user to exchange one cap for another when charge is low and/or distinct storage capacity is desirable. 
       FIG.  10    shows a system  300 , including a storage case  310  along with the audio device  10  (e.g., earbuds  15 ) and additional caps  30  according to various implementations. In some cases, the caps  30 A,  30 B are configured to fit in the storage case  310 . In this depiction, the system  300  is shown including the audio device  10  placed in the storage case  310  along with additional caps  30 A,  30 B. In some cases, the additional caps  30 A,  30 B can include replacement caps of the same, or distinct type as the caps  30  coupled with the bases  20  in the audio device  10 . In various implementations, the caps  30  are sized to fit in the storage case  310  with the base  20 . That is, the storage case  310  can include a first set of slots  320  for accommodating the base  20  while coupled with a cap (e.g., the cap  30  or the additional cap  30 A,  FIG.  9   ), and a second set of slots  330  for accommodating at least one cap  30  not coupled with the base  20 . In the specific implementation depicted in  FIG.  10   , the storage case  310  includes two slots  320  for storing the audio device  10  and two slots  330  for storing the separate caps  30 . 
     In various implementations, the storage case  310  includes a charging case with a power source for charging the audio device  10  when the base  20  and cap  30  are coupled, as well as charging the additional cap(s)  30 . The power source can include a portable power source such as a rechargeable battery and/or an external power connector. In certain implementations, the storage case  310  includes additional electronics such as any of the electronics  40 ,  50  described with reference to the audio device  10  in  FIG.  4   . For example, the storage case  310  can include additional electronics such as a user interface, audio transducer, microphone and/or communications devices (e.g., a radio). In still further implementations, the storage case  310  includes a tool  340  for coupling and/or decoupling the cap(s)  30  from each base  20 . For example, the tool  340  can include a slot sized to engage the decoupling feature  160  between the base  20  and the cap  30 , enabling the user to easily separate the cap from the base  20 . In still further implementations, the tool  340  can include a recess sized to receive the cap  30  and enabling coupling of the cap  30  to the base  20 . The tool  340  is shown on an inner surface of the storage case  310  in the example depiction in  FIG.  10   , however, it is understood that the tool  340  can be located in any position on or in the storage case  310 . 
       FIG.  11    shows another example of a system  400 , including a storage case  410  with slots  320  for storing, and in some cases, charging the combined base  20  and cap  30 . In a first implementation, shown on the left-hand side of  FIG.  11   , the system  400  includes two (e.g., internal) slots  320  for charging a pair of earbuds (shown as audio devices  10 ). In additional implementations, the storage case  410  is modular, and includes a supplemental charging case  420  that is removably coupled with the storage/charging case  410 . The supplemental charging case  420  can be coupled with the storage case  410  at an interface  430 , which in this example, is located between the two slots  320 . However, in other implementations, the supplemental charging case  420  is coupled to the storage case  410  on a side or other inner or outer surface. The supplemental charging case  420  can be mechanically coupled with the storage case  410 , e.g., via fasteners, interlocking components such as male/female connectors or mating threads. In certain implementations, the supplemental charging case  420  includes at least one additional slot  440  for charging a decoupled cap  30 , and an additional power storage device such as an additional battery and/or connector to external power (not shown). 
     In any case, the audio devices  10  described herein can enable extended useful life and greater adaptability when compared with conventional audio devices. These audio devices  10  can be particularly beneficial for in-ear audio device form factors, and in those cases where the audio device  10  includes a hearing assistance audio device. 
     The functionality described herein, or portions thereof, and its various modifications (hereinafter “the functions”) can be implemented, at least in part, via a computer program product, e.g., a computer program tangibly embodied in an information carrier, such as one or more non-transitory machine-readable media, for execution by, or to control the operation of, one or more data processing apparatus, e.g., a programmable processor, a computer, multiple computers, and/or programmable logic components. 
     A computer program can be written in any form of programming language, including compiled or interpreted languages, and it can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. A computer program can be deployed to be executed on one computer or on multiple computers at one site or distributed across multiple sites and interconnected by a network. 
     Elements of figures are shown and described as discrete elements in a block diagram. These may be implemented as one or more of analog circuitry or digital circuitry. Alternatively, or additionally, they may be implemented with one or more microprocessors executing software instructions. The software instructions can include digital signal processing instructions. Operations may be performed by analog circuitry or by a microprocessor executing software that performs the equivalent of the analog operation. Signal lines may be implemented as discrete analog or digital signal lines, as a discrete digital signal line with appropriate signal processing that is able to process separate signals, and/or as elements of a wireless communication system. 
     When processes are represented or implied in the block diagram, the steps may be performed by one element or a plurality of elements. The steps may be performed together or at different times. The elements that perform the activities may be physically the same or proximate one another, or may be physically separate. One element may perform the actions of more than one block. Audio signals may be encoded or not, and may be transmitted in either digital or analog form. Conventional audio signal processing equipment and operations are in some cases omitted from the drawings. 
     In various implementations, components described as being “coupled” to one another can be joined along one or more interfaces. In some implementations, these interfaces can include junctions between distinct components, and in other cases, these interfaces can include a solidly and/or integrally formed interconnection. That is, in some cases, components that are “coupled” to one another can be simultaneously formed to define a single continuous member. However, in other implementations, these coupled components can be formed as separate members and be subsequently joined through known processes (e.g., soldering, fastening, ultrasonic welding, bonding). In various implementations, electronic components described as being “coupled” can be linked via conventional hard-wired and/or wireless means such that these electronic components can communicate data with one another. Additionally, sub-components within a given component can be considered to be linked via conventional pathways, which may not necessarily be illustrated. 
     Other embodiments not specifically described herein are also within the scope of the following claims. Elements of different implementations described herein may be combined to form other embodiments not specifically set forth above. Elements may be left out of the structures described herein without adversely affecting their operation. Furthermore, various separate elements may be combined into one or more individual elements to perform the functions described herein.