Patent Publication Number: US-2011075871-A1

Title: Soft Concha Ring In-The-Ear Hearing Aid

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     The present application claims priority from U.S. Provisional Application No. 61/247,303 entitled SOFT CONCHA RING IN-THE-EAR HEARING AID, filed Sep. 30, 2010, incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to hearing aids. In particular, the present invention pertains to the physical structure used to mount and assemble hearing aid electronic components for wearing in or on the ear of a user. 
     Hearing aids are electrical devices having a microphone to receive sound and convert the sound waves into an electrical signal, some sort of amplification electronics, and a speaker (commonly called a “receiver” in the hearing aid industry) for converting the amplified electronic signal back into sound waves that can be better heard by the user. The electronic circuitry is commonly powered by a replaceable battery. 
     Over the years, great advances have been made in the electronic circuitry. It is now common to have the amplification electronics performed in a digital (rather than analog) realm with a programmable digital signal processor (“DSP”) chip. Of course, with a DSP chip, an analog-to-digital converter must be present either in the microphone, the DSP chip or as a separate component between the microphone and the DSP chip, and a digital-to-analog converter must be present either in the DSP chip, the receiver, or as a separate component between the DSP chip and the receiver. With today&#39;s DSP chips, the hearing aid can be easily programmed so its sound output is not identical to the sound input, but rather is specially customized for the hearing deficiency of a particular user. Today&#39;s DSP chips can also be easily programmed to have differing amplification modes, such as having a different transfer function used in a music concert than in a crowded restaurant. The size of the electronics has greatly decreased over the years, permitting a large variety of different hearing aid styles for mounting and supporting the electronic functions. For a given complexity, the cost of the electronics has also greatly decreased over the years. 
     Despite the great advances in hearing aid electronics, hearing aids are not universally worn by all who have some sort of hearing deficiency—far from it. It turns out that the actual programmable signal gain in the hearing aid is only a small part of the consumer&#39;s decision. In addition to how the hearing aid sounds, users are concerned with how the hearing aid looks, and with how the hearing aid feels. Many users want hearing aids which are as inconspicuous as possible. The hearing aid must fit comfortably, preferably remaining comfortable in a wide variety of conditions (differing health conditions of the wearer, changes in weather, changes in altitude, changes in headgear, etc.). Additionally, the fit of the hearing aid can affect the electronic performance, particularly in feedback modes in conditions when the amplified sound from the receiver is acoustically received by the microphone in a resonant frequency, with the feed forward electronic gain exceeding the acoustic attenuation of the feedback sound. The wide variety of physical wearing conditions affects the acoustic feedback transfer function of the hearing aid, and hearing aids often produce undesirable crackles and whistles during particular and difficult to predict acoustic and physical events. The great advances in hearing aid electronics have not nearly succeeded in universal adoption of hearing aids by all who could benefit. 
     Many different physical styles of hearing aids have developed seeking to take best advantage of the advances in hearing aid electronics. While hearing aids were initially often bulky and body worn (in a shirt pocket, on spectacles, etc.), today most hearing aids are worn and supported entirely by a single ear of the wearer. Some hearing aids have the primary electronics Behind-The-Ear (“BTE”), with most BTE designs having an acoustic tube which is mounted from a BTE receiver into the ear canal. The acoustic tube is secured in the canal by any of a variety of tips, with some of the tips being hard plastic custom shapes, and other tips being standard sizes with some flexibility. Another type of hearing aid, In-The-Ear (“ITE”) hearing aids are constructed of hard plastic that fits into the user&#39;s ear canal, with the primary electronics filling the user&#39;s ear bowl, called the concha. Even smaller devices, In-the-Canal (“ITC”) and Completely-In-the Canal (“CIC”) hearing aids, are also made of hard plastic and fit largely or entirely into the user&#39;s ear canal. Receiver-In-The-Ear (“RITE”) or Receiver-In-Canal (“RIC”) devices position most of the electronics behind the ear and then have a flexible tube with a wire leading to a receiver positioned within the ear canal. 
     With the exception of the very flexible tubes, hard plastic such as acrylic is most often used to hold the electronics and wiring stable. For ITC and CIC devices particularly, the hard plastic shells may be custom shaped to fit the particular shape of the user&#39;s ear canal, but custom shaping is expensive and time consuming in the fitting of a hearing aid. 
     For some ITE or ITC models, a resilient element such as a spring can be used to bias off anatomical structures in the user&#39;s outer ear, generally to push the hearing aid shell into tighter contact with the ear canal and perhaps simultaneously provide an out-of-the-canal structure used to pull the hearing aid out of the ear canal. Resilient or soft materials are also frequently used to make a more comfortable or tighter contact within the user&#39;s ear canal, such as a soft covering on the hard plastic shell to reduce the pressure points pressing against the user&#39;s ear canal. 
     There are weaknesses of all these various designs. BTE and ITE styles are not as discrete in appearance as many users would like. For CICs and ITCs, one-size-fits-most housings are difficult to make comfortable since ear canals have a large variety of shapes and the thin skin over bone and the hard plastic results in sensitivity to any misfits. Another problem is that the microphone location, especially for CICs and ITCs, is near the speaker output. This results in very high feedback. The most common method to attempt to reduce feedback is for the ear canal to be as occluded as possible to reduce the acoustic feedback from the receiver to the microphone. Feedback cancellation algorithms available in modern hearing aid amplifiers help somewhat, but are usually unable to prevent oscillation without the help of some physical blocking of the ear canal. However, physical blocking of the ear canal often reduces comfort of the wearer, at least in some situations (having a cold, riding an elevator, etc.). RITE, RIC and acoustic tube designs also have essentially two different insertion steps, one positioning and attaching the hearing aid electronics relative to the ear, and a second positioning and/or attaching the tube in the ear canal. The insertion process is particularly a problem for elderly users with dexterity limitations. Consistent fits on a day-to-day basis, requiring identical repositioning of the flexible tube and/or receiver, are hard to achieve. 
     Separate from the hearing aid field, earplugs and sound protectors have been developed which are intended to occlude the user&#39;s ear canal as much as possible. For instance, Surefire LLC of Fountain Valley, Calif. makes a variety of earplugs and communication systems earbuds which are usually intended to block out as much ambient noise as possible by sealing to the ear canal wall. For radio communication models which are intended to permit the passage of ambient sound, a central lumen is formed through the ear canal portion of the device. 
     Improved physical hearing aid designs could be made to take better advantage of the advances in electronics. The physical hearing aid designs should be as comfortable as possible to the wearer. The physical hearing aid designs should be pleasing visually, such as being as visibly inconspicuous as possible. The design should accommodate a large variety of ear anatomical shapes, allowing for easy insertion and removal. The physical hearing aid designs should also minimize feedback problems. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention is a hearing aid having a suspension portion received in the wearer&#39;s concha bowl. The suspension portion is flexible and bears off a tragus contact area, an antitragus contact area and an antihelix contact area. Based on forces generated from these concha bowl contact areas, the receiver is suspended in a cantilevered position within the ear canal. The flexibility of the suspension portion at the contact areas ensures a comfortable fit. The receiver is commonly supported in a shell housing portion which is formed of a rigid plastic material. The suspension portion is preferably provided by a flexible ring housing portion which is joined to the more rigid shell housing portion. The annulus of the ring housing portion provides an open concha skin surface, which can naturally reflect sound down the generally open ear canal. The hearing aid makes much more comfortable contact with the concha bowl to hold the receiver in its cantilevered, suspended position. In the preferred embodiment, the microphone is within the flexible ring housing portion. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an elevational side view of common ear anatomy. 
         FIGS. 2 through 5  are side, bottom and front views of the hearing aid of the present invention. 
         FIGS. 6-13  are cross-sectional views of the canal portion of the hearing aid of the present invention, taken alone the respectively numbered cut lines in  FIGS. 3 and 4 . 
         FIG. 14  is the side view of  FIG. 2 , with a tetrahedron added to show the lines measured as distances between the tragus contact area, the antitragus contact area and the antihelix contact area of the preferred hearing aid geometry. 
     
    
    
     While the above-identified drawing figures set forth preferred embodiments, other embodiments of the present invention are also contemplated, some of which are noted in the discussion. In all cases, this disclosure presents the illustrated embodiments of the present invention by way of representation and not limitation. Numerous other minor modifications and embodiments can be devised by those skilled in the art which fall within the scope and spirit of the principles of this invention. 
     DETAILED DESCRIPTION 
     The present invention is an ITE hearing aid  10  which fits within the concha bowl  12  and ear canal  14  of a user&#39;s ear  16 . While external ear anatomy is somewhat complex and can differ greatly from person to person,  FIG. 1  depicts and identifies well-known external ear anatomy which is commonly shared among the vast majority of people. The human ear  16  includes a broad outer structure (called the pinna  18 ) including the ear lobe  20  (lobulus) and the helix  22 . The ear canal  14  is partly obscured by the tragus  24 . The concha bowl  12  lies between the ear canal  14  and the antihelix  26 , with the antitragus  28  and the antihelix  26  slightly obscuring the edge of the concha bowl  12 . The concha bowl  12  includes a lower portion known as the cavum conchae  30  and an upper portion known as the cimba conchae  32 . The antihelix  26  extends around the cimba conchae  32  to a top portion known as the crus inferius antehelicis  34 , and the helix  22  extends forwardly around the crus antehelicis  36  to just above the ear canal  14  terminating in the radix helices  38 . The ear drum and other internal ear structure reside well down the ear canal  14 . In an average adult, the ear canal  14  is about 26 mm long, with its central axis at a slightly forward angle to the plane generally established by the pinna  18  and concha  12 , and with the central axis curving slightly. The ear canal shape (cross-sectional to its central axis) is largely circular or ovular, with an average cross section dimension (diameter) decreasing from about 9 to 7 mm. 
     Generally speaking, ITC and CIC hearing aid bodies reside within the ear canal  14  and maintain their position within the ear  16  by a frictional or compressive fit with the wall of the ear canal  14 . ITE hearing aid body structures, in contrast, reside primarily within the concha bowl  12 . Within the human population, the concha bowl  12  has much less variation in shape than ear canals  14 . However, there is some variation in the concha size. That is, the distance between the tragus  24 , antitragus  28  and the top of the antihelix  26  may be greater or smaller from individual to individual, but will maintain a generally consistent ratio, with the direction of the skin faces of the tragus  24 , antitragus  28  and antihelix  26  being fairly consistent from person to person. The concha bowl  12 , and particularly the side faces of the tragus  24 , antitragus  28  and antihelix  26  defining the concha bowl  12 , is more tolerant of pressure than the ear canal  14  or other internal ear structures. 
     The present invention takes advantage of the more consistent concha bowl shape and higher pressure tolerance to provide a hearing aid  10  which is supported by the concha bowl  12  but which extends in a cantilevering fashion into the ear canal  14 . As shown in  FIGS. 2-5 , the hearing aid  10  includes an electronics portion  40  and a suspension portion  42 . The electronics portion  40  houses at least the receiver  44  (shown in  FIGS. 12 and 13 ) and preferably most of the other electrical components including the battery  46  (shown in dashed lines in  FIGS. 2-5 ) and the DSP chip  48  (shown in  FIGS. 10 and 11 ). The electronics portion  40  also houses the electrical connections (not shown in figures) between these electrical components  44 ,  46 ,  48 . For reference, the battery  46  depicted in the drawings is a conventional size 10 battery, which has a generally cylindrical shape with about a 5.7 mm diameter and a 3.5 mm height. With the current availability of microminiature hearing aid components, the battery  46  is easily the largest electrical component of the hearing aid  10 . For instance, the DSP chip  48  may be generally rectangular of about 2.5×3.5×1 mm, and the receiver  44  may be generally rectangular of about 5×2×2 mm. 
     The electronics portion  40  includes a housing  50  which has a shell  52  and a battery door  54  (only visible in  FIG. 5 ) hinged to the shell  52 . The battery door  54  typically carries the battery  46  and can be pivoted to an open position for replacement of the battery  46 . In its preferred form, the housing  50  of the electronics portion  40  is formed separately from the suspension portion  42 . For instance, the shell  52  (including its face plate if using a face plate assembly method) and the battery door  54  may both be molded from a polymer material such as acrylic, or any other traditional bio-compatible plastic material commonly used for hearing aid housings. Such traditional hearing aid plastics typically have a durometer of greater than about 50 on the Shore D scale. 
     While the durometer of the plastic material of the shell  52  and battery door  54  is important, more significant is the relative stiffness of the material during use of the hearing aid  10 , which is a function of durometer, shear strength, and geometry such as wall thickness. The shell  52  and the battery door  54  are both formed with sufficient wall thicknesses and geometry so as to be dimensionally stable during use and operation of the hearing aid  10 . That is, since the purpose of the shell  52  and battery door  54  is primarily to house and protect the electrical connections between the electrical components, the wall thicknesses are chosen to be sufficiently thick that the housing  50  will not substantially compress or deflect if/when in contact with ear canal tissue during insert, removal or use of the hearing aid  10 , relative to the compression or deflection of the tissue itself. Typically this will be a material and geometry which provides a stiffness of 1000 N/m or more over the first 0.5 mm of deflection. 
     The suspension portion  42  of the hearing aid  10  resides within the concha bowl  12  and supports the weight of the hearing aid  10  through compressive forces against the concha skin surfaces. The hearing aid structure of the present invention is not intended to significantly contact or press into the ear canal wall, and to provide the suspension concept of the invention the contact surfaces with the concha bowl  12  must be spread out over a substantial area. Essentially, the suspension portion  42  includes a tragus contact area  56 , an antitragus contact area  58  and an antihelix contact area  60  (denoted in  FIGS. 2-5 ), each of which exert a mild compressive force against their corresponding skin surface. A generally vertical rib  62  extends between the tragus contact area  56  and the antihelix contact area  60 . An arcuate rib  64  extends between the antitragus contact area  58  and the antihelix contact area  60 , such that the suspension portion  42  has an overall shape like a D. 
     The tragus contact area  56 , the antitragus contact area  58  and the antihelix contact area  60  need not have any identifiable marking on the hearing aid  10  to the wearer, but rather are denoted in the drawings merely to explain the operation of the structure within the concha bowl  12 . The point of denoting the tragus contact area  56 , the antitragus contact area  58  and the antihelix contact area  60  is not to suggest that the suspension portion  42  makes “point contact” with the concha skin or even necessarily makes contact at all at these specific points with any wearer&#39;s specific concha anatomy. Instead, the tragus contact area  56 , the antitragus contact area  58  and the antihelix contact area  60  each conceptually represent a center point where a mild compressive force is exchanged between the suspension portion  42  and any wearer&#39;s concha anatomy. As shown in  FIG. 1 , the tragus  24 , the antitragas  28  and the antihelix  26  all have an undercut that secures each of the tragus contact area  56 , the antitragus contact area  58  and the antihelix contact area  60  in place. 
     The tragus contact area  56 , the antitragus contact area  58  and the antihelix contact area  60  jointly define a base plane for the hearing aid  10 , with the compressive force from the concha anatomy being generally directed inward in this base plane. The spacing between the tragus contact area  56 , the antitragus contact area  58  and the antihelix contact area  60  allow the suspension portion  42  to remain generally stationary relative to the ear  16  even as the wearer accelerates, decelerates and turns his or her head this way and that. Moreover, the spacing between the tragus contact area  56 , the antitragus contact area  58  and the antihelix contact area  60  all cause the hearing aid  10  to suspend the receiver  44  (e.g., the apex of the electronics portion  40 ) in a relatively stationary location within the ear canal  14  without significantly biasing off any wall of the ear canal  14 . Much like three spaced legs of a stool can be used to support the seat, the forces from the tragus contact area  56 , the antitragus contact area  58  and the antihelix contact area  60  can withstand gravitational and accelerational forces and moments on the cantilevered, suspended receiver  44  (and any other cantilevered structure of the electronics portion  40 ). 
     This concept of suspending the receiver  44  centered in the ear canal  14  based off biasing forces from the concha bowl  12  is very different from the bearing concepts of prior art ITE structures, which either leave the receiver  44  substantially outside the ear canal  14  or bias off the ear canal  14 . This concept of suspending the receiver  44  centered in the ear canal  14  based off biasing forces from the concha bowl  12  is very different from ITC and CIC structures, which necessarily bias off the ear canal wall. Even with any supporting spring types of structures, the prior art spring concept has generally been to bias the hearing aid  10  into and against the ear canal  14 , not to achieve a cantilevered, suspended position for the receiver  44 . This concept of suspending the receiver  44  centered in the ear canal  14  based off biasing forces from the concha bowl  12  is also very different from RITE, RIC and acoustic tube structures which have too great of flexibility and require separate positioning and support of the in-the-canal portion of the hearing aid. 
     In addition to a portion of the shell  52  residing outside the ear canal  14 , the preferred suspension portion  42  includes a concha ring structure  66  which is formed separately from the shell  52  and battery door  54 . The concha ring structure  66  is made from a generally soft and flexible polymer. For example, the concha ring structure  66  can be formed of a resilient polymer commonly considered a rubbery material, such as having a durometer of less than about 90 on the Shore A scale, with the preferred rubbery material having a Shore A durometer of between 35 and 45, and most preferably a Shore A durometer of approximately 40. The preferred material for the concha ring structure  66  is a translucent PVC material, such as 3019-40/45 Clear 003, an injection-moldable flexible PVC compound with rubber like flexibility and softness available from AlphaGary of Leominster, Mass. This material has a specific gravity of 1.13 (ASTM D 792), a durometer A, 10 Second (⅛″/24 hr) value of 40/45, a durometer A, 10 Second (¼″/24 hr) value of 35/45 (both ASTM D2240), a tensile strength (75 mil) of 1200 psi, an elongation (75 mil) of 525%, and a modulus 100% (75 mil) of 340 psi (all ASTM D 638). 
     Like the material for the shell  52  and battery door  54 , more important than its material properties are the relative flexibility of the concha ring structure  66  relative to the concha anatomy, which is a function of durometer, shear strength, and geometry. Namely, when a mild compressive force is delivered in the base plane for the hearing aid  10  on each of the tragus contact area  56 , the antitragus contact area  58  and the antihelix contact area  60 , the concha ring structure  66  should substantially compress or deflect relative to the compression or deflection of the tissue itself. Numerically, the present invention should have a geometry and material designed to have a flexibility between the tragus contact area  56 , the antitragus contact area  58  and the antihelix contact area  60  of about 200 N/m or less over the first millimeter or two of deflection. 
     The concha ring structure  66  is joined to the shell  52  at a top junction  68  and at a bottom junction  70 , such as with an epoxy adhesive. Alternatively, the shell  52  and the concha ring structure  66  can be formed with a mating attachment configuration, such as a flexible button/rigid loop attachment structure. Alternatively, the concha ring structure could be formed to wrap around the shell  52  either outside the canal or shallowly in the canal. Either way, at least two of the tragus contact area  56 , antitragus contact area  58  and antihelix contact area  60  are preferably provided on the concha ring structure  66  so that the suspension portion  42  as a whole allows substantial compression or deflection of the tragus contact area  56 , the antitragus contact area  58  and the antihelix contact area  60 . 
     The microphone  72  for the preferred embodiment is in the antihelix area, with a microphone port  74  visible in the view of  FIG. 5 . Small wires  76  connect the microphone  72  to the electronics portion  40 . In the preferred manufacturing method, the concha ring portion  66  is molded and solidified prior to assembly of the microphone  72  therein. The concha ring portion  66  can be cut to provide an opening for the microphone  72 , including slitting the concha ring portion  66  where it is desired to run the microphone wires  76 . The microphone  72  is then connected to its wires  76 , with the microphone  72  and its wires  76  jointly inserted into the opening and slit. Alternatively, a slot could be molded into the concha ring portion  66 , with the microphone  72  and its wires  76  then placed into the slot and then the wires  76  (and possibly part of the microphone  72 , but leaving an open microphone port  74 ) held in place with an adhesive fill of the slot. As another alternative, the microphone  72  and its wires  76  could be mold insitu into the concha ring portion  66 . 
     Locating the microphone  72  in the antihelix area has the advantage that it is fairly far from the receiver  44 , which reduces the feedback problem. Locating the microphone  72  in the antihelix area also provides good directional performance for the microphone  72 , with the natural ear shape reflecting sounds toward the microphone  72  and with the microphone  72  moving with the natural inclination of the wearer&#39;s head. Locating the microphone  72  in the antihelix area also hides the microphone  72  somewhat by the antihelix  26  of the ear  16 , giving the hearing aid  10  good cosmetic appeal. The microphone  72  could alternatively be located in the electronics portion  40 , which would lead to a more secure electrical wiring of the microphone  72  and a simpler assembly process, but would not allow the separation between the microphone  72  and the receiver  44  achieved with the preferred embodiment. 
     As noted, the hearing aid structure of the present invention is not intended to significantly contact or press into the ear canal wall, best shown with reference to the cross-sectional shapes of  FIGS. 6-13 , which depict a series of cross-sectional cuts taken generally perpendicular to the axis of the ear canal  14  when the canal portion of the hearing aid  10  is suspended therein. The receiver port  78  is in the ear canal  14 , but the distal end of the electronics portion  40  is much smaller than the canal diameter. This results in very minimal contact with the canal wall. The canal portion of the hearing aid  10  primarily includes a concha side face  80  and a tragus side face  82  forming the longer sides of the generally rectangular cross-sectional views, and two faces forming the shorter sides of the generally rectangular cross-sectional views, defining a central axis  84  of the shell  52 . The central axis  84  extends at a slight angle (typically 10-20°) to the base plane defined by the tragus contact area  56 , the antitragus contact area  58  and the antihelix contact area  60 . The primary concern in orienting the shell  52  relative to the suspension portion  42  is for the battery  46  to best fit at the ear canal opening, while extending the receiver  44  into the ear canal  14 . 
     The preferred dimensions of the hearing aid  10  are best described with reference to  FIG. 14 , which shows a tetrahedron formed by connecting the tragus contact area  56  T, the antitragus contact area AT, the antihelix contact area AH and the apex A of the shell  52  (coinciding with the receiver port  78 ). When show in this view (with the triangle T-AT-AH being in the plane of the page), the apex A is just outside the contact area. The height or altitude of the apex A relative to the base plane (T-AT-AH contact point plane) is between 5 mm and 25 mm, and more preferably at a height between 10 mm and 15 mm, such that the apex is between ⅓ and ⅔ of the standard depth of most ear canals  14 . The preferred altitude of the apex A relative to the base plane is about 13 mm. To provide the stable suspension forces for the suspended apex, each of the tragus contact area T, the antitragus contact area AT and the antihelix contact area AH should be between 10 and 30 mm apart. The distance between the tragus contact area T and the antitragus contact area AT is the shortest of the three distances in the base plane, between 10 mm and 20 mm. In the preferred embodiment, the distance between the tragus contact area T and the antitragus contact area AT is about 14 mm. The distance between the antihelix contact area AH and the antitragus contact area AT is the longest of the three distances in the base plane, between 20 mm and 30 mm. In the preferred embodiment, the distance between the antihelix contact area AH and the antitragus contact area AT is about 26 mm. The distance between the antihelix contact area AH and the tragus contact area T is between 15 mm and 25 mm, with a preferred dimension of about 20 mm. With the preferred altitude of the apex and spacing within the base plane, the distance between the tragus contact area T and the apex A is about 13 mm, the distance between the antitragus contact area AT and the apex A is about 18 mm, and the distance between the antihelix contact area AH and the apex A is about 23 mm. These preferred dimensions provide for the suspension of the apex A within the ear canal  14  as being cantilevered from the base defined by the concha bowl  12 . 
     While there is little variation in shape, there is some variation in the concha size among the human adult population. The generally arcuate rib  64  can bend slightly to accommodate a fairly wide range of concha bowl sizes. Further, the preferred dimensions can easily be modified to fit a wider range of different concha sizes, such as a large version with dimensions 10% greater than the preferred dimensions given and a small version with dimensions 10% smaller than the preferred dimensions given. Another alternative is to design suspension portion  42  with a means to adjust its size. One way to adjust the size of the suspension portion  42  is to create joints in the ring where added length can be inserted, such as in the arcuate rib  64  between the antihelix contact area  60  and the antitragus contact area  58 . Another means to adjust the size of the suspension portion  42  is to provide elements attachable to the edges of the ring to increase the dimensions between the tragus contact area  56 , the antitragus contact area  58  and the antihelix contact area  60 . 
     The concha side face  80  of the shell  52  does not make significant contact with the ear canal  14 , such that skin on concha side of the ear canal  14  continuously flows without contact by the hearing aid  10  to the concha face. The separation distance between the concha side face  80  of the shell  52  and the skin is usually about 2 to 3 mm. 
     The face of the concha bowl  12  itself is preferably left open and not covered by the suspension portion  42  of the hearing aid  10 . The annular opening in the concha ring provides several benefits. By having the annular concha ring, sound is received by the majority of the concha skin surface in a more natural way than most ITE hearing aids which cover the concha face. Because the shell  52  does not fit tightly within the ear canal  14 , sound received on the concha skin surface is reflected down the ear canal  14  in a more natural way than possible with most ITC and CIC designs. 
     In some designs, a fully continuous ring for the suspension portion  42  may not be necessary. However, the preferred suspension structure borrows from the ear plug designs of Surefire LLC to include not only a complete ring, but also a top lobe  86  and a small bottom lobe  88  to more securely hold the suspension structure relative to the concha bowl  12 . U.S. Pat. No. 7,394,910 of Surefire LLC is incorporated by reference. Regardless, the important consideration is the layout and relative flexibility of the tragus contact area  56 , the antitragus contact area  58  and the antihelix contact area  60 , with or without a full ring structure and with or without the top and bottom lobes  86 ,  88 . 
     The battery compartment is located behind the tragus  24  in the preferred embodiment. The tragus  24  hides the battery  46  somewhat giving an attractive cosmetic look. The exposed surface of the battery door  54  can be colored to match the shadow of the ear canal  14  that is normally seen in this location. 
     Tests were performed to provide a detailed numerical basis for the comparison between the flexibility of the concha ring/shell structure of the preferred embodiment as compared to prior art hard shell hearing aids. Specifically, the hearing aid  10  was clamped at the shell  52 , and a push force was applied at either the antitragus contact area  58  or the antihelix contact area  60 . The direction of the push force was in the base plane, toward the center of the suspension portion  42 . The push force as a function of deflection on the preferred embodiment was as follows: 
     
       
         
           
               
             
               
                 TABLE I 
               
             
            
               
                   
               
               
                 PUSH IN AT ANTITRAGUS CONTACT AREA 
               
            
           
           
               
               
               
            
               
                 deflection (mm) 
                 Force (mN) 
                 Stiffness (N/m) 
               
               
                   
               
            
           
           
               
               
               
            
               
                 0.0 
                 0 
                   
               
               
                 0.5 
                 65 
                 130 
               
               
                 1.0 
                 110 
                 110 
               
               
                 1.5 
                 150 
                 100 
               
               
                   
               
            
           
         
       
     
                     TABLE II                  PUSH IN AT ANTIHELIX CONTACT AREA                         deflection (mm)   Force (mN)   Stiffness (N/m)                                 0.0   0           0.5   70   140       1.0   120   120       1.5   170   110       2.0   200   100                    
It can thus be seen that the hearing aid  10  can be readily adapted over a fairly wide range of concha sizes and structure, but without generating uncomfortable forces on the concha  12  of the wearer. In contrast, a prior art hard shell hearing aid responded to a push test (a HANSATON hearing aid with the other side of the hearing aid clamped) as follows:
 
                     TABLE III                  PRIOR ART PUSH TEST                         deflection (mm)   Force (mN)   Stiffness (N/m)                                 0.0   0           0.2   400   2000       0.3   500   1600       0.4   650   1600       0.5   800   1600                    
The present invention has a flexibility in excess of ten times that of a hard plastic shell.
 
     The present invention was further push tested by clamping the antitragus and antihelix contact areas  58 ,  60 , and applying a horizontal (generally perpendicular to the central axis  84 ) and a vertical (generally in line with the central axis  84 ) force to the apex A of the shell  52 , with results shown in Tables IV and V below: 
     
       
         
           
               
             
               
                 TABLE III 
               
             
            
               
                   
               
               
                 PUSH VERTICAL AT APEX 
               
            
           
           
               
               
               
            
               
                 deflection (mm) 
                 Force (mN) 
                 Stiffness (N/m) 
               
               
                   
               
            
           
           
               
               
               
            
               
                 0.0 
                 0 
                   
               
               
                 1.0 
                 90 
                 90 
               
               
                 1.5 
                 120 
                 80 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE IV 
               
             
            
               
                   
               
               
                 PUSH HORIZONTAL AT APEX 
               
            
           
           
               
               
               
            
               
                 deflection (mm) 
                 Force (mN) 
                 Stiffness (N/m) 
               
               
                   
               
            
           
           
               
               
               
            
               
                 0.0 
                 0 
                   
               
               
                 3.0 
                 35 
                 12 
               
               
                 4.0 
                 38 
                 10 
               
               
                 5.0 
                 41 
                 8 
               
               
                   
               
            
           
         
       
     
     It can thus be seen that the present invention, even if coming in contact with the ear canal  14  (such as often happens during insertion of the hearing aid  10  into the ear  16 , but also could happen if not properly aligned with the ear  16  or if the shape of the wearer&#39;s ear canal  14  were drastic out of norm), will only place a minimal force on the tissue of the ear canal  14 . Even though the shell  52  is formed of the same material as prior art shells, the relative flexibility of the apex A of the hearing aid  10  is on the order of 100 times greater than in the prior art design. 
     As a further basis for comparison, horizontal and vertical apex push tests were taken of a prior art “soft tip” design, specifically of a UNITRON FUSE hearing aid, with the following results: 
     
       
         
           
               
             
               
                 TABLE V 
               
             
            
               
                   
               
               
                 PRIOR ART PUSH VERTICAL AT APEX 
               
            
           
           
               
               
               
            
               
                 Deflection (mm) 
                 Force (mN) 
                 Stiffness (N/m) 
               
               
                   
               
            
           
           
               
               
               
            
               
                 0.0 
                 0 
                   
               
               
                 0.5 
                 155 
                 310 
               
               
                 1.0 
                 285 
                 285 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE VI 
               
             
            
               
                   
               
               
                 PRIOR ART PUSH HORIZONTAL AT APEX 
               
            
           
           
               
               
               
            
               
                 deflection (mm) 
                 Force (mN) 
                 Stiffness (N/m) 
               
               
                   
               
            
           
           
               
               
               
            
               
                 0.0 
                 0 
                   
               
               
                 0.5 
                 160 
                 320 
               
               
                 1.0 
                 300 
                 300 
               
               
                   
               
            
           
         
       
     
     The UNITRON FUSE hearing aid is a CIC design, which is intended to flex with the natural movement of the wearer&#39;s ear canal  14 . Again, even if/when the apex comes into contact with the ear canal  14 , the present invention is substantially more flexible over the length of the device even than prior art soft tip designs. 
     The concha ring design of this hearing aid  10  is thus more comfortable than traditional designs that are held into place by contact with the ear canal  14 . The concha bowl  12  has much less variation in shape than ear canals  14 , and the concha bowl  12  is more tolerant of pressure points than the ear canal  14 . 
     The concha ring design is also easy and intuitive for the user to put into place. The concha ring structure  66  is relatively easy to grasp and makes it relatively easy for the user&#39;s fingers to manipulate the location and orientation of the hearing aid  10  when inserting the hearing aid  10  into the user&#39;s ear  16 . The concha ring structure  66  is also relatively easy for the user to grab when the user&#39;s desires to remove the hearing aid  10  from his or her ear. The concha ring structure  66  leads to a very consistent positioning of the hearing aid  10  relative to the user&#39;s ear  16  over multitudes of insertions and removals, leading to a more consistent performance of the hearing aid  10 . 
     Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention. For instance, the electronics housing portion  50  could be formed integrally with the suspension portion  42 , with the electrical components molded into the material of the suspension portion  42 . With current manufacturing conditions, forming the electronics housing portion  50  with a hard shell  52  permits a face plate assembly process well known and used in the hearing aid industry, with the hard shell  52  of the electronics housing portion  50  containing and protecting the sensitive electrical connections between the electrical components. The electronics housing portion  50  also allows the battery  46  to be housed with a moving battery door  54 , which enables user-replacement of the battery  46  in a well known manner and with the battery door  54  concealing the battery  46  during use of the aid  10 . However, the suspension concepts of the present invention could be equally applied even if the hearing aid housing was formed of a single material with sufficient flexibility.