Patent Publication Number: US-2023164501-A1

Title: Adjustable Fit Hearing Aids

Description:
TECHNICAL FIELD 
     This disclosure relates to hearing aids, and, particularly, to adjustable fit hearing aids. 
     BACKGROUND 
     Getting a hearing aid has traditionally required consumers to see a licensed professional, which requires appointments, tests and fittings. In the end, consumers (patients) may end up spending thousands of dollars - an expense not covered by Medicare or most insurance companies. 
     Thanks to a federal law passed in 2017, consumers may soon have access to over-the-counter (OTC) hearing aids that are expected to bring down the price and hassles associated with purchasing traditional hearing aids. These new devices are expected to cost less than traditional hearing aids. 
     The variability of ear geometry across the population makes it difficult to produce a universal-fit hearing aid. Manufacturers will need a simple and cost-effective way to allow consumers to find an OTC solution with an appropriate fit. 
     A conventional wire system of a traditional receiver-in-canal (RIC) hearing aid  100  is shown in  FIG.  1   . A typical RIC hearing aid  110  includes a behind-the-ear portion  102  that includes a battery, a microphone, and a sound processor housed in a casing  104  designed to sit behind a user’s ear resting against a rear surface of the user’s pinna. This behind-the-ear portion  102  of the hearing aid  100  has a small wire  106  (wiring cable) designed to run around the user’s ear and into an earpiece  108  that is designed to sit in the user’s ear canal. The earpiece  108  carries a speaker, also known a “receiver,” “driver,” “electro-acoustic transducer,” or simply “transducer.” Conventional hearing aids also often include a compliant tip  110  (or “dome”) on the earpiece  108  for engaging with a user’s ear canal. 
     Typically, an audiologist makes a measurement and selects the appropriate wire length from a manufacturer-supplied set  200 , see  FIG.  2   . A manufacturer may offer between three and five different wire lengths to accommodate the full span of ear geometry. 
     The wire provides both an electrical connection and a mechanical coupling between the ear and the device. Using the wrong length leads to the device being unstable and falling off the patient. See  FIG.  3    for an example of a small ear fitted with the correct wire length  300  (left)and one that is too long  302  (right), and  FIG.  4    for a larger ear fitted with a wire that is too short  400  (left) and a correct wire length  402  (right). 
     Conventional behind-the-ear (BTE) hearing aids have a similar form factor, with a case that sits behind a user’s ear, and attached ear piece that directs sound to the user’s ear canal. While both RIC and BTE hearing aids are technically behind-the-ear, the BTE has more components behind the ear. In that regard, the BTE hearing aids have the microphone, receiver (speaker), battery, and sound processor all behind the ear, with just a tube running around the ear and into the ear piece for conducting acoustic energy from the speaker to the user’s ear canal. 
     SUMMARY 
     All examples and features mentioned below can be combined in any technically possible way. 
     In one aspect, a hearing aid includes an earpiece, a casing, and coupling member. The earpiece is configured to sit at least partially within the user’s ear canal when worn. The casing supports a sound processor and a microphone and is configured to sit behind a user’s ear and in contact with the user’s pinna when worn. The coupling member couples the casing to the earpiece. The coupling member has an effective length that is adjustable to accommodate users with different ear geometries. 
     Implementations may include one of the following features, or any combination thereof. 
     In some implementations, the coupling member includes one or more compliant, spring-biased bends that can be straightened under tension to accommodate larger ear geometries. 
     In certain implements, the one or more complaint, spring-biased bends provide the coupling member with an S-shape. 
     In some cases, the coupling member includes a polymeric tube and wherein the compliant, spring-biased bends are formed by the polymeric tube. 
     In certain cases, the coupling member includes wiring and a cover that surrounds the wiring. 
     In some examples, the complaint, spring-biased bends are formed by the wiring. 
     In certain examples, the complaint, spring-biased bends are formed by the cover. 
     In some implementations, the coupling member has regions of varying stiffness including a first region proximate the casing having a first stiffness, and a second region arranged between the first region and the earpiece having a second stiffness that is two to five times less stiff than the first stiffness. 
     In certain implementations, the casing includes a plurality of connection points and the coupling member may be selectively coupled to any one of the connection points to adjust an effective length of the coupling member. 
     In some cases, the coupling member includes a pre-strained wire formed from a shape memory alloy which extends when heated to adjust the effective length of the coupling member. 
     In certain cases, the coupling member includes a first portion that includes a coiled coupling section encased in an elastomer. The elastomer provides compliance thereby allowing the coiled coupling section to be stretched to adjust the effective length of the coupling section. 
     In some examples, the coupling member includes a first conductor portion that is electrically coupled to the sound processor in the casing and a second conductor portion that is electrically coupled to a receiver supported in the earpiece. The first and second conductor portions are slidable relative to each other and are configured to maintain an electrical connection therebetween as they are displaced, thereby to adjust the effective length of the coupling member. 
     In certain examples, the coupling member includes a corrugated section that includes a series of corrugations that can be collapsed on themselves to shorten the effective length of the coupling member and can be extended to increase the effective length of the coupling member. 
     In some implementations, the coupling member includes a plurality of links that are hinged together at joints. The links can be folded on top of one another to shorten the effective length of the coupling member and can be unfolded to increase the effective length of the coupling member. 
     In certain implementations, the casing defines an aperture and a cavity within which the sound processor is disposed. The effective length of the coupling member can be adjusted by pushing or drawing a portion of the coupling member into the cavity via the aperture. 
     In some cases, the hearing aid includes an adjustment member supported by the housing and moveable relative thereto. The adjustment member is operable to draw the portion of the coupling member into the cavity. 
     In certain cases, the hearing aid includes a guide member that is disposed within the cavity and arranged to help guide the portion of the coupling member that is received within the housing. 
     In some examples, the coupling member is segmented and wherein the effective length of the coupling member can be adjusted by adding or removing one or more segments. 
     In certain examples, the coupling member is at least partially formed of a material that stiffens when heat is applied to it, and the effective length of the coupling member is configured to be adjusted by pushing or drawing a portion of the coupling member into the cavity via the aperture while the coupling member is in a loose flexible state, and the effective length is fixed in place by applying heat to stiffen the coupling member. 
     In some implementations, the earpiece includes a housing, a first dome, and second dome. The housing has a first end that is coupled to the coupling member and a second, opposite end that defines a nozzle configured to deliver acoustic energy to a user’s ear canal when worn. The first dome is supported by the nozzle and the second dome is supported by the housing in a position between the nozzle and the first end of the housing. 
     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. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a perspective view of a typical receiver-in-canal (RIC) hearing aid. 
         FIG.  2    is a set of manufacturer-provided wires (left) and measurement (right) for a hearing aid. 
         FIG.  3    is an example of a small ear with a hearing aid having a correctly fit wire (left) and a wire that is too long (right). 
         FIG.  4    is an example of a larger ear with a hearing aid having a wire that is too short (left) and a correctly fit wire (right). 
         FIG.  5    is a schematic side view of a hearing aid having a plurality of connection points (e.g., sockets) for adjusting an effective length of a coupling member. 
         FIG.  6    is a schematic side view of a hearing aid having a coupling member with an integrated spring in the form of an S-curve. 
         FIG.  7    shows the hearing aid of  FIG.  6    being used to accommodate both a small ear (left) and large ear (right) while maintaining comfort and stability. 
         FIG.  8    is a schematic side view of a hearing aid having a coupling member with an integrated spring in the form of a loop. 
         FIG.  9    is a schematic side view of a hearing aid having a coupling member with an integrated spring in the form of a coiled section encased in an elastomer. 
         FIG.  10    is a schematic side view of a hearing aid having a coupling member with an integrated spring in the form of a rotational spring. 
         FIG.  11    is a schematic side view of a hearing aid having an adjustable length coupling member with slidable sections. 
         FIG.  12    is a schematic side view of a hearing aid having an adjustable length coupling member with telescoping sections. 
         FIGS.  13 A and  13 B  are schematic side views of a hearing aid having an adjustable length coupling member with links. 
         FIGS.  14 A and  14 B  are schematic side views of a hearing aid having an adjustable length coupling member with an expandable/collapsible corrugated section. 
         FIGS.  15 A and  15 B  are schematic side views of a hearing aid having an adjustable length coupling member with a shape memory material to allow a pre-strained configuration to extend when heated/when current is applied. 
         FIG.  16    is a schematic side view of a hearing aid that uses a removable spacer in the form of a double-sided connector for adjusting an effective length of a coupling member. 
         FIGS.  17 A and  17 B  are schematic side views of a hearing that user removable spacers in the form of removable wire/tube segments for adjusting for adjusting an effective length of a coupling member. 
         FIG.  18    is a schematic side view of a hearing aid that uses interchangeable couple members of contrasting length for adjusting the effective length. 
         FIG.  19 A- 22   are schematic side views of various implementations of a hearing aid in which an effective length of a coupling member can be adjusted by accommodating a section of the coupling member within a casing of a behind-the-ear portion of the hearing aid. 
         FIG.  23    is a schematic side view of an earpiece having a stabilizing feature disposed within an ear canal. 
     
    
    
     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 implementations. 
     DETAILED DESCRIPTION 
     This disclosure relates to coupling members for connecting a behind-the-ear portion of a hearing aid to an earpiece. The coupling members of this disclosure enable accommodation for different ear geometries. 
     Multiple Connection Points 
       FIG.  5    illustrates an exemplary embodiment of a hearing aid  500  constructed according to this disclosure. The hearing aid  500  includes an earpiece  502  and a casing  504 , which houses electronics  505  including a microphone  506 , sound processor  508 , and battery  510  for powering the microphone  506  and processor  508 . The casing  504  is designed to sit behind a user’s ear resting against a rear surface of the user’s pinna. 
     To accommodate different ear geometries, a plurality (three shown) of connectors  512  (e.g., sockets) are located along the outside, or inside the casing  504 . A coupling member  514  with a mating connector  516  may be plugged into any one of the sockets  512 . This effectively allows a single coupling member  514  to achieve multiple lengths between the casing  504  and the earpiece  502 . The opposite end of the coupling member  514  may lay against the external surface of the casing  504  or may be recessed into a channel  518  along the length of the casing  504  or may be contained inside the casing  504 . 
     A curvature of the coupling member  514  may be formed such that it follows a curvature of the casing  504  when adjusted for small ear geometries. A section of the coupling member  514  near the housing end may be more flexible than a section near the opposite, earpiece end to allow adjustment of the compound curve of the coupling member  514  while retaining stiffness near the earpiece  502  for ease of insertion and removal from a user’s ear. 
     In the case of a RIC style hearing aid, the coupling member  514  may comprise wiring; e.g., a pair of electrically conductive wires contained in a conduit, e.g., a polymeric sleeve or tube, that enables the transmission of electrical energy from the casing  504  to the receiver  520  in the earpiece  502 . In this case, the connectors  512  on the casing  504  are electrical connectors, e.g., electrical sockets, and the mating connector  516  is an electrical connector to enable an electrical connection to be formed between the electronics in the casing  504  and the receiver  520  in the earpiece  502 . 
     A similar configuration may be utilized for a behind-the-ear (BTE) style hearing aid. In the BTE configuration, a plurality of acoustic contact points (e.g., acoustic sockets) may be located along the outside, or inside the casing. The acoustic contact points may be acoustically coupled to the receiver housed in the casing. A single tube with a mating acoustic contact point may be plugged into any one of the sockets and may be used to convey acoustic energy from the receiver in the casing to the earpiece. This effectively allows a single tube to achieve multiple lengths between the casing and the earpiece. The opposite end of the tube may lay against the external surface of the casing or may be recessed into a channel along the length of the casing or may be contained inside the casing. 
     Integrated Spring 
     In another implementation, to eliminate the need for multiple coupling lengths to accommodate for different ear geometries, or at least reduce the number of lengths, a coupling member comprising spring-like bends is proposed. 
     The coupling member must meet two, opposing design requirements: (1) provide enough tension in the wire to keep the device in place, particularly on smaller ears and (2) be soft enough to extend in length while not applying an uncomfortable amount of force, particularly on larger ears. 
     Finite element analysis can be used to determine what wire shapes meet the required stiffness. While many designs may meet these requirements, an example of an S-shaped coupling member is shown in  FIG.  6   . However, other spring configurations, including other curved shapes, e.g., a “C-shaped curve,” are also contemplated. 
       FIG.  6    shows an exemplary hearing aid  600  that includes an earpiece  602  and a casing  604 , which houses a microphone  606 , sound processor  608 , and battery  610  for powering the microphone  606  and processor  608 . As noted above, the coupling member  612  is provided with an integrated spring in the form of an S-curve that includes a first curve  614  between the casing  604  and the earpiece  602 ; and a second curve  616  between the first curve  614  and the earpiece  602 . In some cases, a third curve  618  may be provided between the second curve  616  and the earpiece  602 . In some cases, the first, second and third curves  614 ,  616 ,  618  may reside in respective regions of contrasting stiffness (e.g., least stiff near the earpiece  602  and more stiff near the casing  604 . In that regard, the first curve  614  may be in a region having a stiffness of greater than 1000 Newtons per meter (N/m); the second curve  616  may be in a second region having a stiffness of 200 to 400 Newtons per meter (N/m); and the third curve  618  may be in a third region having a stiffness of 400 to 1000 Newtons per meter (N/m). The overall stiffness of the integrated, composite spring is 200 to 400 Newtons per meter (N/m). 
     This coupling member  612 , in its undeformed shape, securely fits a small ear  700  (left), but allows enough stretching to accommodate a larger ear  702  (right) too as shown in  FIG.  7    with the same ears used in  FIG.  3    and  FIG.  4   . 
     The implementation illustrated in  FIG.  6    may be utilized in either a RIC style hearing aid or a BTE style hearing aid. In the case of a RIC style hearing aid, the coupling member  612  may comprise electrically conductive wiring; e.g., a pair of electrically conductive wires contained in a conduit, e.g., a polymeric sleeve or tube, that enables the transmission of electrical energy from the casing  604  to the receiver in the earpiece  602 . In this case, the spring-like bends may be formed in the electrically insulated sleeve or tube that surrounds the wires, and/or in the conductive wires themselves. 
     Alternatively, in the case of a BTE style hearing aid, the coupling member  612  may comprise a tube (e.g., a polymeric tube) that enables the transmission of acoustic energy from the receiver in the casing  604  to the earpiece. In this case, the spring-like bends may be formed in the tube. 
     While an S-shaped coupling member is shown and described with respect to  FIG.  6   , in other implementations, the coupling member may be provided with an integral spring in the form of a loop  800 , as shown in  FIG.  8   , which provides tension in the wire to keep the device in place, particularly on smaller ears, and allows the coupling member to extend in length to accommodate larger ears. The integrated spring may have a spring constant of 200 to 400 Newtons per meter (N/m). 
       FIG.  9    illustrates another example of a hearing aid  900  in which the coupling member  902  connecting a casing  904  of a behind-the-ear portion and an earpiece  906  includes a first portion  908  that includes a coiled coupling section  910  that is encased in an elastomer  912 . The elastomer  912  provides some compliance allowing the coiled coupling section  910  to be stretched so that the hearing aid  900  can better fit larger ears, while contracting to eliminate slack in the wire for smaller ears. Suitable elastomers include TPU or silicone. 
     A second portion  914  of the coupling member  902  is disposed between the coiled coupling section  910  and the casing  904 . The second portion  914  may be formed integrally with the coiled coupling section  910 . 
     A third portion  916  of the coupling member  902  is disposed between the coiled coupling section  910  and the earpiece  906 . The third portion  916  may be formed integrally with the coiled coupling section  910 . 
     In the case of a RIC style hearing aid, the coiled coupling section  910  may comprise electrically conductive wiring; e.g., a pair of electrically conductive wires contained in a conduit, e.g., a polymeric sleeve or tube, that enables the transmission of electrical energy from the casing  904  to a receiver in the earpiece  906 . In this case, the coils in the coiled coupling section  910  may be formed in the electrically insulated sleeve or tube that surrounds the wires, and/or in the conductive wires themselves. As mentioned above, the second and third portions  914 ,  916  of the coupling member  902  may be formed integrally with the coiled coupling section  910  such that the coupling member  902  includes wiring, e.g., a pair of electrically conductive wires, contained in a conduit, e.g., a polymeric sleeve or tube, that extends from the casing  904  at one end to the earpiece  906  at its opposite end with the coiled coupling section  910  being formed between the two ends. 
     Alternatively, in the case of a BTE style hearing aid, the coiled coupling section  910  may comprise a tube (e.g., a polymeric tube) that enables the transmission of acoustic energy from the receiver in the casing  904  to the earpiece. In this case, the coils in the coiled coupling section may be formed in the tube. The second and third portions  914 ,  916  of the coupling member  902  may be formed integrally with the coiled coupling section  910  out of the same piece of tubing. 
     In some cases, the coiled coupling section  910  may be configured to act as a tension spring thereby allowing the coiled coupling section  910  to be stretched so that the hearing aid  900  can better fit larger ears, while contracting under its own spring force to eliminate slack in the wire for smaller ears, and, thereby, potentially obviating any need for the elastomer. 
       FIG.  10    illustrates yet another implementation of a hearing aid  1000  in which a rotational spring  1002  is integrated into a coupling member  1004 , e.g., at the point where the coupling member  1004  is joined to a casing  1006 . The rotational spring  1002  allows the coupling member  1004  to be stretched so that the hearing aid  1000  can better fit larger ears, while contracting under its own spring force to eliminate slack in the wire for smaller ears. 
     In the case of a RIC style hearing aid, the rotational spring  1002  may be formed by the conduit (e.g., polymeric tube) containing the electrically conductive wires, and/or by the electrically conductive elements themselves. 
     For a BTE style hearing aid, the rotational spring  1002  may be formed by the tube that conducts acoustic energy between the casing  1006  and the earpiece  1008 . 
     Sliding Sections 
       FIG.  11    illustrates an implementation of a RIC style hearing aid  1100  that accommodates user’s with different ear geometries by incorporating electrical conductor portions that are slidable relative to each other to adjust the effective length of the coupling member  1102 . In that regard, the coupling member  1102  includes a first conductor portion  1104  that is electrically coupled to electronics enclosed in the casing  1106  and is mechanically coupled to the casing  1106 . A second conductor portion  1108  is electrically coupled to a receiver in the earpiece  1110  and is mechanically coupled to the earpiece  1110 . The first and second conductor portions  1104 ,  1108  are slidable (arrows  1111 ) relative to each other and are configured to maintain an electrical connection therebetween as they are displaced. To help maintain the electrical connection between the first and second conductor portions  1104 ,  1108 , the first and second conductor portions  1104 , 1108  may be held in close contact with each other, e.g., via a surrounding tube or a loop. In some cases, the first and/or second conductor portions  1104 , 1108  may be provided with a protrusion that projects outwardly toward the other one of the first and second conductor portions  1104 ,  1108  to assist in establishing/maintaining the electrical contact therebetween. Such a protrusion may be arranged to slide up and down a length of the adjacent conductor portion to ensure good electrical contact regardless of the relative position of the first and second conductor portions  1104 ,  1108 . 
     Alternatively, or additionally, the first and/or second conductor portion  1104 ,  1108  may be slidably received within an electrical connector  1112 , and the electrical connector  1112  may assist in establishing and/or maintaining an electrical connection between the first and second conductor portions  1104 ,  1108 . 
     Telescoping Jacket 
       FIG.  12    illustrates another implementation of a hearing aid  1200  in which a coupling member  1202  is provided with telescoping section  1204  that is operable to adjust its effective length. In the illustrated example, the telescoping section  1204  has three distinct potions including a first portion  1206  that is coupled to the casing  1208 ; a second portion  1210  that is slidably received within the first portion  1206 ; and a third portion  1212  that is coupled an ear piece  1214  and slidably received within the second portion  1210 . The first, second, and third portions  1206 ,  1210 ,  1212  may be formed of discrete pieces of polymeric tubing having contrasting diameters. The length of the coupling member  1202  is adjustable between a fully collapsed position, for a small ear, and a fully extended position, for a larger ear. 
     In the fully collapsed position, the second portion  1210  may be fully received within the first portion  1206  and the third portion  1212  may be fully received in the second portion  1210 . 
     In the fully extended position, the second portion  1210  extends outwardly from the first portion  1206  by a maximum amount and the third portion  1212  extends outwardly from the second portion  1210  by a maximum amount. 
     Intermediate lengths are achieved by extending the second portion  1210  outwardly of the first portion  1206  only partially, and/or by extending the third portion  1212  outwardly from the second portion  1210  only partially. 
     In the case of a RIC style hearing aid, the telescoping section  1204  may surround wiring that extends between the casing  1208  and the earpiece  1214  for powering a receiver in the earpiece  1214 . Excess wiring (slack) in the fully collapsed position, or a partially collapsed position, may be accommodated in the tubing forming the telescoping section  1204  and/or in the casing  1208 . 
     In the case of a BTE style hearing aid, the tubing forming the telescoping section  1204  may also be used to transfer acoustic energy from a receiver in the casing  1208  to the earpiece  1214 . 
     Links 
       FIGS.  13 A &amp;  13 B  illustrate another implementation of a hearing aid  1300  in which a coupling member  1302 , extending between a casing  1301  and an earpiece  1303 , includes a plurality of links  1304  that are hinged together at joints  1306 . The links  1304  can be folded on top of one another to shorten the effective length of the coupling member  1302  as shown in  FIG.  13 A , or one or more of the links  1304  can be unfolded to increase the effective length of the coupling member  1302 . as shown in  FIG.  13 B . 
     Expandable/Collapsible Corrugations 
       FIGS.  14 A &amp;  14 B  illustrates yet another implementation of a hearing aid  1400  in which a coupling member  1402  is provided with a corrugated section  1404  similar to what may be found on conventional flexible drinking straws. The corrugated section  1404  includes a series of corrugations  1406  that can be collapsed on themselves to shorten the effective length of the coupling member  1402  ( FIG.  14 A ), or may be extended, e.g., by applying a force at either end of the coupling member  1402  to increase the effective length of the coupling member  1402  ( FIG.  14 B ). As in the implementations described above, in a RIC style hearing aid, the coupling member  1402  may support wiring for delivering an electrical signal from the casing  1408  to the earpiece  1410 . Alternatively, in a BTE style hearing aid, the coupling member  1402  may be configured to deliver acoustic energy from the casing  1408  to the earpiece  1410 . 
     Shape Memory Alloy 
     In yet another implementation of a hearing aid  1500 , illustrated in  FIGS.  15 A and  15 B , a coupling member  1502  may include a shape memory alloy that allows a pre-strained wire to extend when heated. For example,  FIG.  15 A  shows the coupling member  1502  as formed with a loop  1504 .  FIG.  15 B  shows the shape of the coupling member  1502  with current applied. The effective length of the coupling member  1502  is thus controlled by applying currently to eliminate the loop and thereby increase the effective length of the coupling member. In some cases, a current for adjusting the shape and length of the coupling member  1502  may be applied by electronics  1506  housed within the casing  1508 . 
     Removable Spacers 
     In other implementations, spacers may be used to extend the effective length of the coupling member. For example,  FIG.  16    illustrates an implementation of a hearing aid  1600  that includes a double-sided connector  1602  that is arranged between the casing  1604  and the coupling member  1606 . In one example, the double-sided connector  1602  includes a male side  1608  that may be coupled to a female connector  1610  on the casing  1604 , and a female side  1612  that may receive a male connector  1614  arranged on an end of the coupling member  1606 . Additional double-sided connectors may be added to further increase the effective length of the coupling member  1606 . 
     Still, in another implementation of a hearing aid  1700 , a coupling member  1702  may include a plurality of segments, such as shown in  FIGS.  17 A and  17 B . With reference to  FIG.  17 A , the coupling member  1702  includes a first segment  1704  that is configured to be coupled to the casing  1706 , and a second segment  1708  that is coupled to the earpiece  1710 . As shown in  FIG.  17 A , the first segment  1704  may be coupled directly to the second segment  1708  to provide a shortest length coupling member  1702 . Alternatively, as shown in  FIG.  17 B , the first segment  1704  may be coupled to the second segment  1708  via a plurality of intervening segments  1712  (3 shown). The segments may be coupled together, e.g., via electrical connectors  1714  arranged at the ends of the segments  1704 ,  1708 ,  1712 . 
     Alternatively, as shown in  FIG.  18   , a hearing aid  1800  includes a coupling member  1802   a - c  (generally “ 1802 ”) may be releasably coupled, e.g., via electrical connectors  1804  to both the casing  1806  and the earpiece  1808 , and a plurality of coupling members  1802  of different sizes (e.g., small (“ 1802   a ”), medium (“ 1802   b ”), and large (“ 1802   c ”)) may be provided. A user can select the size that most closely matched his/her ear geometry and then make the appropriate connection to the casing  1806  and the earpiece  1808 . This does not eliminate the need to provide a plurality of coupling member sizes, but it does eliminate the need to provide a different earpiece for each size of coupling member  1802 . 
     Slide Inside 
     In some cases, the coupling member may be provided with an extended length and excess slack may be accommodated in the casing. For example,  FIG.  19 A  illustrates an implementation of a hearing aid  1900  in which excess slack in the coupling member  1902  may be fed into an aperture  1904  in the casing  1906 . The casing  1906  may define a cavity  1   908  within which the excess slack is received and retained. An O-ring  1910  may be provided in the aperture  1904  to provide a seal between the coupling member  1902  and the casing  1906  and/or to provide a friction surface that inhibits movement of the coupling member  1902  once the length has been set. The user may feed the excess slack into the cavity  1908  by pinching the coupling member  1902  and pushing it into the aperture  1904  until the desired length is achieved. 
     Slide Inside - Guide Member 
     A section of rigid tube  1912  ( FIG.  19 A ) or a guide rib  1914  ( FIG.  19 B ), may be disposed within the cavity  1908  to help guide the portion of the coupling member  1902  that is received within the casing  1906 . One end of the coupling member  1902  may be connected to the electronics  1916  in the casing  1906  with the opposite end being coupled to the earpiece  1918 . The rigid tube  1912  and/or guide rib  1914  may be formed, e.g., molded, integrally with the casing  1906 . 
     With reference to  FIG.  19 B , in some cases, the coupling member  1902  may be attached, e.g., soldered to or coupled via electrical connectors, at one end to a flexible printed circuit board  1920  that is disposed within the cavity  1908  defined by the casing  1906 . The flexible printed circuit board  1920  may be coupled, e.g., soldered or connected via electrical connectors, at its opposite end, the electronics  1916 . In some cases, the flexible printed circuit board  1920  may be integrated into a printed wiring board that supports the electronics  1916  in a flex-rigid construction. The flexible printed circuit board  1920  may provide additional flexibility within the cavity  1908 ; i.e., it may be more flexible than the coupling member  1902  itself. 
     Slide Inside - Thumb Adjust 
     In some cases, an adjustment mechanism may be supported on the casing to help adjust the effective length of the coupling member. For example,  FIG.  20    illustrates an implementation of a hearing aid  2000  in which an adjustment member  2002  is attached to the coupling member  2004  and is slidably supported on the casing  2006 . The adjustment member  2002  may support one or more electrical contacts  2008  that are electrically coupled to the coupling member  2004  and are arranged to establish an electrical connection with an electrical contact  2010  within the casing  2006 . The adjustment member  2002  may slide within a slot  2012  defined by the casing  2006  and the electrical contact  2008  supported on the adjustment member  2002  may slide along the electrical contact  2010  within the casing  2006 . The electrical contact  2010  within the casing  2006  may be an exposed conductive surface on a printed wiring board  2014  which may also support other components of the electronics  2016 . The user may adjust the effective length of the coupling member  2004  by sliding the adjustment member  2002 , relative to the casing  2006 , with his/her thumb, as indicated by arrow  2018 . 
       FIG.  21    illustrates another configuration of a hearing aid  2100  in which an adjustment member  2102  is coupled to a coupling member  2104  and is slidably supported on a casing  2106 . The adjustment member  2102  may slide within a slot  2108  defined by the casing  2106 . In the implementation illustrated in  FIG.  21   , an electrically conductive rigid member  2110  is affixed to, and moves with, the adjustment member  2102 . The rigid member  2110  may be formed of a strip of metal, e.g., copper. One end of the coupling member  2104  is electrically and mechanically coupled to a first end of the electrically conductive rigid member  2110 , e.g., via an electrical connector or solder joint, and a second end of the electrically conductive rigid member  2110  is coupled to the electronics  2112 , e.g., via wiring  2114 . The effective length of the coupling member  2104  is adjusted by displacing the adjustment member  2102  along the slot  2108 . In other configurations, the coupling member  2104  may be directly coupled to the electronics  2112 , mechanically and electrically, and the adjustment member  2102  may be mechanically coupled to the coupling member  2104  to adjust the length of the coupling member  2104 . Excess slack in the coupling member  2104  is accommodated in a cavity  2116  defined by the casing  2106 . 
       FIG.  22    illustrates another implementation of a hearing aid  2200  in which the adjustment member  2202  is configured in the form of a reel  2204  that is supported on the casing  2206  and can be rotated, e.g., via the user’s thumb, to draw in/wind up excess slack in the coupling member  2208  to adjust the effective length of the coupling member  2208 . A first end portion  2210  of the coupling member  2208  is coupled to the electronics  2212  and may be run through a center of the reel  2204 . A second portion  2214  of the coupling member  2208  is at least partially wound around the reel  2204 . 
     When feeding, e.g., pushing or drawing, the coupling member into the casing, such as described above with respect to  FIG.  19 A -22, it may be desirable if the coupling member is relatively loose/flexible so that it better conforms to the interior of the casing. However, a stiffer coupling member can be beneficial for helping to keep the hearing aid stable when it worn. 
     In some implementations, to help balance these competing interests, the coupling member may be formed, at least partially, from a material that is stiffened when exposed to heat. In that regard, the coupling member may incorporate a shrink wrap material such as PVC, polyolefin, polyethylene, and polypropylene. In which case, the coupling member can be adjusted to length in a loose/flexible state, and, once the coupling member has been adjusted to the desired length, it can then be exposed to heat, e.g., via a heat gun, to stiffen the material. The stiffening of the coupling member can help to hold the coupling member at the selected length and it can also provide for stabilization of the earpiece in the user’s ear when the hearing aid is worn. 
     Alternatively, or additionally, the earpiece may be configured for added stability. For example,  FIG.  23    illustrates an implementation of an earpiece  2300  that includes a second dome  2302  for additional stability. The earpiece  2300  includes a housing  2304  that is configured to sit at least partially within a user’s ear canal  2306 . The housing  2304  may be formed of a rigid material, e.g., a rigid plastic such as Acrylonitrile Butadiene Styrene (ABS), Polycarbonate/Acrylonitrile Butadiene Styrene (PCB/ABS), polyetherimide (PEl), or stereolithography (SLA) resin). At a first end, the housing  2304  is coupled to a coupling member  2308 . At a second, opposite end, the housing  2304  defines a nozzle  2310  to deliver acoustic energy to the user’s ear canal  2306 . A first dome  2312  is supported on the nozzle  2310  for engaging with a user’s ear canal. The first dome  2312  helps to retain the earpiece  2300  in the user’s ear canal. The second dome  2302  is supported on the housing  2304  and is positioned between the first dome  2312  and the first end of the housing  2304 . The second dome  2302  also engages the user’s ear canal and provides for additional stability of the earpiece  2300  when worn. The first and second domes  2312 ,  2302  may be made of any suitable soft flexible materials including, for example, silicone, polyurethane, polynorbornene (e.g., Norsorex® material available from D-NOV GmbH of Vienna, Austria), thermoplastic elastomer (TPE), and/or fluoroelastomer. 
     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. 
     A number of implementations have been described. Nevertheless, it will be understood that additional modifications may be made without departing from the scope of the inventive concepts described herein, and, accordingly, other embodiments are within the scope of the following claims.