Patent Publication Number: US-2023156415-A1

Title: Implantable sound sensors with non-uniform diaphragms

Description:
BACKGROUND 
     Field of the Invention 
     The present invention generally relates to implantable sound sensors for implantable hearing prostheses. 
     Related Art 
     Hearing loss is a type of sensory impairment that is generally of two types, namely conductive and/or sensorineural. Conductive hearing loss occurs when the normal mechanical pathways of the outer and/or middle ear are impeded, for example, by damage to the ossicular chain or ear canal. Sensorineural hearing loss occurs when there is damage to the inner ear, or to the nerve pathways from the inner ear to the brain. 
     Individuals who suffer from conductive hearing loss typically have some form of residual hearing because the hair cells in the cochlea are undamaged. As such, individuals suffering from conductive hearing loss typically receive an auditory prosthesis that generates motion of the cochlea fluid. Such auditory prostheses include, for example, acoustic hearing aids, bone conduction devices, and direct acoustic stimulators. 
     In many people who are profoundly deaf, however, the reason for their deafness is sensorineural hearing loss. Those suffering from some forms of sensorineural hearing loss are unable to derive suitable benefit from auditory prostheses that generate mechanical motion of the cochlea fluid. Such individuals can benefit from implantable auditory prostheses that stimulate nerve cells of the recipient’s auditory system in other ways (e.g., electrical, optical and the like). Cochlear implants are often proposed when the sensorineural hearing loss is due to the absence or destruction of the cochlea hair cells, which transduce acoustic signals into nerve impulses. An auditory brainstem stimulator is another type of stimulating auditory prosthesis that might also be proposed when a recipient experiences sensorineural hearing loss due to damage to the auditory nerve. 
     SUMMARY 
     In one aspect, a sound sensor implantable in a recipient of a hearing prosthesis is provided. The sound sensor comprises: a biocompatible housing comprising a cavity having an opening at a first end of the housing; a non-uniform diaphragm attached to the housing so as to hermetically seal the opening; a coupling member configured to mechanically couple the non-uniform diaphragm to a vibrating structure of the recipient’s middle or inner ear such that the non-uniform diaphragm vibrates in response to vibration of the vibrating structure; and a vibrational sensor disposed in the housing and configured to detect vibration of the non-uniform diaphragm and generate signals representative of the detected vibrations. 
     In another aspect, an implantable sound sensor is provided. The implantable sound sensor comprises: a biocompatible housing; a diaphragm attached to the housing, wherein the diaphragm comprises at least a first section and a second section having a thickness that is less than a thickness of the first section, wherein the diaphragm is mechanically coupled to a vibrating structure of the recipient’s middle or inner so as to vibrate in response to vibration of the vibrating structure; and a vibrational sensor disposed in the housing and configured to detect vibration of the diaphragm and generate signals representative of the detected vibrations. 
     In another aspect, a sound sensor implantable in a recipient of a hearing prosthesis is provided. The sound sensor comprises: a biocompatible housing comprising an opening; a diaphragm positioned at the opening, wherein the diaphragm comprises a first thickness at a geometric center thereof that is greater than a thickness at a periphery of the diaphragm; a coupling member configured to mechanically couple the diaphragm to a vibrating structure of the recipient’s middle or inner ear such that the diaphragm vibrates in response to vibration of the vibrating structure; and a vibrational sensor disposed in the housing and configured to detect vibration of the diaphragm and generate signals representative of the detected vibrations, 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the present invention are described herein in conjunction with the accompanying drawings, in which: 
         FIG.  1 A  is a schematic illustrating a hearing prosthesis implanted in a recipient, in accordance with certain embodiments presented herein; 
         FIG.  1 B  is a schematic block diagram of the hearing prosthesis of  FIG.  1 A ; 
         FIG.  2 A  is a schematic side view of an implantable sound sensor having a non-uniform diaphragm coupled to a vibrating structure of a recipient, in accordance with certain embodiments presented herein; 
         FIG.  2 B  is a schematic cross-sectional view of the implantable sound sensor of  FIG.  2 A ; 
         FIG.  2 C  is bottom-perspective view of the non-uniform diaphragm of the implantable sound sensor of  FIG.  2 A   
         FIGS.  3 A,  3 B, and  3 C  are cross-sectional views illustrating operation of a conventional diaphragm; 
         FIGS.  4 A,  4 B, and  4 C  are cross-sectional views illustrating operation of a non-uniform diaphragm, in accordance with certain embodiments presented herein; 
         FIG.  5    is a cross-sectional view of a non-uniform diaphragm, in accordance with certain embodiments presented herein; 
         FIG.  6    is a cross-sectional view of a non-uniform diaphragm, in accordance with certain embodiments presented herein; 
         FIG.  7    is a cross-sectional view of a non-uniform diaphragm, in accordance with certain embodiments presented herein; 
         FIG.  8    is a cross-sectional view of a non-uniform diaphragm, in accordance with certain embodiments presented herein; 
         FIG.  9    is a cross-sectional view of a non-uniform diaphragm, in accordance with certain embodiments presented herein; 
         FIG.  10    is a cross-sectional view of a non-uniform diaphragm, in accordance with certain embodiments presented herein; 
         FIG.  11    is a cross-sectional view of a non-uniform diaphragm, in accordance with certain embodiments presented herein; 
         FIG.  12    is a cross-sectional view of a non-uniform diaphragm, in accordance with certain embodiments presented herein; 
         FIG.  13    is a cross-sectional view of a non-uniform diaphragm, in accordance with certain embodiments presented herein; 
         FIG.  14    is a cross-sectional view of a non-uniform diaphragm, in accordance with certain embodiments presented herein; 
         FIG.  15    is a cross-sectional view of a non-uniform diaphragm, in accordance with certain embodiments presented herein; 
         FIG.  16    is a cross-sectional view of a non-uniform diaphragm, in accordance with certain embodiments presented herein; 
         FIG.  17    is a cross-sectional view of a non-uniform diaphragm, in accordance with certain embodiments presented herein; 
         FIG.  18    is a cross-sectional view of a non-uniform diaphragm, in accordance with certain embodiments presented herein; 
         FIG.  19    is a cross-sectional view of a non-uniform diaphragm, in accordance with certain embodiments presented herein; 
         FIG.  20    is a cross-sectional view of a non-uniform diaphragm, in accordance with certain embodiments presented herein; and 
         FIG.  21    is a cross-sectional view of a non-uniform diaphragm, in accordance with certain embodiments presented herein. 
     
    
    
     DETAILED DESCRIPTION 
     Presented herein are implantable sound sensors that include a diaphragm mechanically coupled to a vibrating structure of a recipient’s middle or inner ear. The diaphragm includes a central region and a peripheral region, where the thickness of the central region is greater than the thickness of the peripheral region. 
     Embodiments of the present invention are described herein primarily in connection with one type of implantable hearing prosthesis, namely a totally or fully implantable cochlear implant. As used herein, a totally implantable cochlear implant refers to an implant that is capable of operating, at least for a period of time, without the need for any external device. It would be appreciated that embodiments of the present invention may also be implemented in a cochlear implant that includes one or more external components. It would be further appreciated that embodiments of the present invention may be implemented in any partially or fully implantable hearing prosthesis now known or later developed, including, but not limited to, acoustic hearing aids, auditory brain stimulators, middle ear mechanical stimulators, hybrid electro-acoustic prosthesis or other prosthesis that electrically, acoustically and/or mechanically stimulate components of the recipient’s outer, middle or inner ear. 
       FIG.  1 A  is perspective view of a totally implantable cochlear implant, referred to as cochlear implant  100 , implanted in a recipient.  FIG.  1 B  is a block diagram of the cochlear implant  100 . For ease of description,  FIGS.  1 A and  1 B  will be described together. 
     The recipient in which cochlear implant  100  is implanted has an outer ear  101 , a middle ear  105  and an inner ear  107 . Components of outer ear  101 , middle ear  105  and inner ear  107  are described below, followed by a description of cochlear implant  100 . 
     In a fully functional ear, outer ear  101  comprises an auricle  110  and an ear canal  102 . An acoustic pressure or sound wave  103  is collected by auricle  110  and channeled into and through ear canal  102 . Disposed across the distal end of ear canal  102  is a tympanic membrane  104  which vibrates in response to sound wave  103 . This vibration is coupled to oval window or fenestra ovalis  112  through three bones of middle ear  105 , collectively referred to as the ossicles  106  and comprising the malleus  108 , the incus  109  and the stapes  111 . Bones  108 ,  109  and  111  of middle ear  105  serve to filter and amplify sound wave  103 , causing oval window  112  to articulate, or vibrate in response to vibration of tympanic membrane  104 . This vibration sets up waves of fluid motion of the perilymph within cochlea  140 . Such fluid motion, in turn, activates tiny hair cells (not shown) inside of cochlea  140 . Activation of the hair cells causes appropriate nerve impulses to be generated and transferred through the spiral ganglion cells (not shown) and auditory nerve  114  to the brain (also not shown) where they are perceived as sound. 
     As shown, cochlear implant  100  comprises components which are temporarily or permanently implanted in the recipient (i.e., under the skin/tissue of the recipient). Cochlear implant  100  is shown in  FIG.  1 A  with an external device  142  which, as described below, is configured to provide power to the cochlear implant. 
     In the illustrative arrangement of  FIGS.  1 A and  1 B , the external device  142  may comprise a power source (not shown) disposed in an off-the ear (OTE) housing. As such, the external device  142  is sometimes referred to as an OTE unit or OTE component  142 . The OTE component  142  also includes components of a transcutaneous energy transfer link, referred to as an external energy transfer assembly. The transcutaneous energy transfer link is used to transfer power (and in certain cases data) to cochlear implant  100 . As would be appreciated, various types of energy transfer, such as infrared (IR), electromagnetic, capacitive and inductive transfer, may be used to transfer the power and/or data from OTE component  142  to cochlear implant  100 . In the illustrative embodiments of  FIG.  1 A , the external energy transfer assembly comprises an external coil  130  that forms part of an inductive radio frequency (RF) communication link. External coil  130  is typically a wire antenna coil comprised of multiple turns of electrically insulated single-strand or multi-strand platinum or gold wire. OTE component  142  also includes a magnet (not shown) positioned within the turns of wire of external coil  130 . It should be appreciated that the external device shown in  FIG.  1 A  is merely illustrative, and other external devices, such as a behind-the ear (BTE) component may be used with embodiments of the present invention. 
     Cochlear implant  100  further comprises a main implantable component  120 , an elongate electrode assembly  118 , and an implantable sound sensor  150 . The main implantable component  120  comprises an internal energy transfer assembly  132 , a sound processor  152 , stimulator unit  154 , and a power source  156 . The internal energy transfer assembly  132 , which is a component of the transcutaneous energy transfer link, comprises a primary internal/implantable coil  136  and transceiver  135  configured to receive power (and possibly data) from OTE component  142 . In the illustrative embodiment, the energy transfer link comprises an inductive RF link and implantable coil  136  is a wire antenna coil comprised of multiple turns of electrically insulated single-strand or multi-strand platinum or gold wire. 
     The sound sensor  150  is implanted in a cavity formed in mastoid bone  119  so as to extend, in this embodiment, into the middle ear cavity. Sound sensor  150  may be secured within the recipient via bracket or other mounting unit (not shown in  FIGS.  1 A or  1 B ). 
     In operation, sound sensor  150  is configured to detect sound received in a recipient’s ear through the use of vibrations or pressure variations that occur in or along the natural path that is followed by acoustic waves in the ear. More specifically, sound sensor  150  senses vibration of a structure of the recipient’s middle ear  105 , such as ossicles  106 , or inner ear  107 , such as vibration of fluid within one of the recipient’s body cavities (e.g., inner ear canals, cochlear ducts, etc.). The vibration of the recipient’s ear structure, referred to herein as “vibrating structure,” is the result of receipt of acoustic waves that travel from the recipient’s outer ear  101  to the middle ear  105  and inner ear  107 . That is, the received acoustic waves impinge upon the vibrating structure of the middle or inner ear structures, creating vibration of the vibrating structure. In the embodiment illustrated in  FIG.  1 A , the sound sensor  150  detects sound based on vibration of the recipient’s middle ear bones, and more specifically, based on vibration of incus  109  (i.e., incus  109  is the vibrating structure in  FIG.  1 A ). 
     As described further below, the implantable sound sensor  150  comprises a non-uniform diaphragm  164  ( FIG.  1 A ) mechanically coupled to the incus  109  via a coupling member  166  ( FIG.  1 A ). As such, the non-uniform diaphragm  164  vibrates in response to vibration of incus  109 . The sound sensor  150  includes a vibration sensor (not shown in  FIGS.  1 A or  1 B ) that is configured to detect vibration of the non-uniform diaphragm  164  and convert the detected vibrations into electrical signals, sometimes referred to herein as microphone signals, which are provided to the sound processor  152  in the main implantable component  120  (e.g., via a cable). In  FIG.  1 B , these microphone signals are represented by arrow  158 . The sound processor  152  is configured convert the microphone signals  158  received from the implantable sound sensor  150  into data signals, represented in  FIG.  1 B  by arrow  160 . The stimulator unit  154  generates electrical stimulation signals based on the data signals  160 . The electrical stimulation signals are delivered to the recipient via elongate electrode assembly  118 . 
     More specifically, elongate electrode assembly  118  has a proximal end connected to main implantable component  120 , and a distal end implanted in cochlea  140 . Electrode assembly  118  extends from main implantable component  120  to cochlea  140  through mastoid bone  119 . In some embodiments electrode assembly  118  may be implanted at least in basal region  116 , and sometimes further. For example, electrode assembly  118  may extend towards apical end of cochlea  140 , referred to as cochlea apex  134 . In certain circumstances, electrode assembly  118  may be inserted into cochlea  140  via a cochleostomy  122 . In other circumstances, a cochleostomy may be formed through round window  121 , oval window  112 , the promontory  123 , or through an apical turn  147  of cochlea  140 . 
     Electrode assembly  118  comprises a carrier member  145  formed from a resiliently flexible material, and a longitudinally aligned and distally extending array  146  of electrodes  148 , sometimes referred to as electrode array  146  herein, disposed along a length of the carrier member  145 . Although electrode array  146  may be disposed on the carrier member  145 , in most practical applications, the electrode array  146  is integrated into the carrier member  145 . As such, electrode array  146  is referred to herein as being disposed in carrier member  145 . As noted, a stimulator unit  154  generates stimulation signals which are applied by electrodes  148  to cochlea  140 , thereby stimulating auditory nerve  114 . 
     As noted, cochlear implant  100  comprises a totally implantable prosthesis that is capable of operating, at least for a period of time, without the need for OTE component  142 . Therefore, cochlear implant  100  further comprises a rechargeable power source  156  that stores power received from OTE component  142 . The power source  156  may comprise, for example, a rechargeable battery. During operation of cochlear implant  100 , the power stored by the power source  156  is distributed to the various other implanted components as needed. Although  FIG.  1 B  shows the power source  156  located in main implantable component  120 , in other embodiments the power source  156  may be disposed in a separate implanted location. 
     An embodiment of implantable sound sensor  150  is described next below with reference to  FIGS.  2 A and  2 B , referred to herein as implantable sound sensor  250  comprising a non-uniform diaphragm  264 .  FIG.  2 A  is a schematic perspective view of the implantable sound sensor  250 , while  FIG.  2 B  is a cross-sectional view of the implantable sound sensor  250 .  FIG.  2 C  is a bottom-perspective of the non-uniform diaphragm  264  separated from the rest of the implantable sound sensor  250 . For ease of description,  FIGS.  2 A- 2 C  will be described together. 
     The implantable sound sensor  250  includes a biocompatible housing  262  defining a cavity  261  with an opening at a first end  263  of the housing. The diaphragm  264  is disposed at the first end  263  of the housing  262 . In particular, the diaphragm  264  is attached to the housing  262  so as to hermetically seal the opening at the first end  263  of the housing (i.e., prevent the ingress of bodily fluids into the housing  262 ). The diaphragm  264  may be welded to the housing  262 , formed with (e.g., unitary with) the housing, etc. 
     In the example of  FIGS.  2 A and  2 B , the housing  262  has a substantially tubular shape. The tubular shape may have a cylindrical or elliptical cross-sectional shape. Other shapes, such as prismatic with square, rectangular, or other polygonal cross-sectional shapes may also be used in alternative embodiments. However, a cylindrical shape may be advantageous for purposes of implantation and manufacture. 
     The implantable sound sensor  250  also comprises a coupling member  266  having a first end  268  and a second end  269 . The first end  268  of the coupling member  266  is mechanically coupled to a vibrating structure  270  (e.g., ossicles) of a recipient’s body, while the second end  269  of the coupling member  266  is secured to the non-uniform diaphragm  264 . 
     The vibrating structure  270  of the recipient’s body is a part of the recipient’s body, such as part of the recipient’s middle or inner ear, which is configured to vibrate as a result of the receipt of acoustic waves that travel from the recipient’s outer ear to the middle ear and/or inner ear  107 . That is, the received acoustic waves result in the vibration of the middle or inner ear structures, or travel through the middle ear cavity, creating vibration of the fluid within the cavities. The vibrating structure  270  may be, for example, any of the recipient’s eardrum, ossicles (including any of the malleus, incus, or stapes), oval window, round window, horizontal canal, posterior canal, superior canal, etc. A physician, surgeon, or other trained medical professional typically makes the determination of which inner or middle ear structure to mechanically couple to the first end  268  of the coupling member  266 . 
     The mechanical coupling between the first end  268  of the coupling member  266  and the vibrating structure  270  may be accomplished in a variety of ways. For example, in some embodiments, the first end  268  can be a surface-to-surface mechanical contact with a slight loading force to hold the first end  268  in place against the vibrating structure  270 . In other embodiments, the first end  268  may be secured to the vibrating structure  270  with bone cement or another type of biocompatible adhesive. 
     As noted above, the second end  269  of the coupling member  266  is secured/attached to the non-uniform diaphragm  264 . As such, the vibrations of the vibration structure  270  are relayed to the non-uniform diaphragm  264  via (through) the coupling member  266 . As described further below, the non-uniform diaphragm  264  is flexible and configured to vibrate in response to vibration of the coupling member  266 . 
     As noted, the diaphragm  264  is disposed at the first end  263  of the housing  262 . Disposed in the housing  262  is a vibration sensor  272  and transmitter circuitry (transmitter)  274 . The vibration sensor  272  may be any of an electret microphone, an electromechanical microphone, a piezoelectric microphone, a microelectro-mechanical systems (MEMS) microphone, an accelerometer, an optical interferometer, a pressure sensor, or any other type of vibration sensor now known or later developed. A gas (air) or liquid-filled vibration chamber  276  exists between the diaphragm  264  and the vibration sensor  272 . For example, in embodiments where the vibration sensor  272  is an electret microphone, MEMS microphone, accelerometer, or optical interferometer, the vibration chamber  276  may be filled with gas such as helium or another gas. For embodiments where the vibration sensor  272  is a piezoelectric microphone or pressure sensor, the vibration chamber  276  may be filled with a liquid such as an oil, silicone gel, or other liquid. In operation, the vibration sensor  272  is configured to detect vibration/deflection of the diaphragm  264  and generate electrical signals  273  based at least in part on the detected vibrations. 
     In certain embodiments, electrical signals  273  generated by the vibration sensor  272  are provided to the transmitter circuitry  274  via a wire  275  or other similar electrical connection mechanism. The transmitter circuitry  274  may include one or more discrete circuit components, one or more integrated circuits, and/or a special-purpose processor configured to prepare or condition the electrical signals  273  (e.g., amplification, etc.) for transmission to a sound processor, such as sound processor  152  shown and described with respect to  FIG.  1 B . The transmitter circuitry  274  is configured to send the raw or conditioned/processed electrical signals, referred to herein as microphone signals, to the sound processor via a wired or wireless communications link (not shown in  FIGS.  2 A and  2 B ). The communications link, which is represented in  FIG.  2 B  by arrow  237  may, in certain embodiments, also be used to provide operating power to the implantable sound sensor  250  in some embodiments. 
     As noted above, the non-uniform diaphragm  264  is flexible and configured to vibrate in response to vibration of the coupling member  266 . Additionally, in the embodiments presented herein, the non-uniform diaphragm  264  is comprised of (formed as) multiple different sections/portions that have different thicknesses. More specifically, as shown in  FIGS.  2 B and  2 C , the non-uniform diaphragm  264  comprises a first or central section/region  280  having a first thickness (D 1 ) and a second or peripheral section/region  282  having a second thickness (D 2 ) that is less than the thickness of the central region  280 . As shown in  FIG.  2 C , the central region  280  has a general cylindrical shape (circular cross-sectional shape), and the peripheral region  282  comprises a ring-shape surrounding the central region  280  (i.e., extending around the outer edge of the central region  280 ). That is, the non-uniform diaphragm  264  has a greater thickness in the geometric center/middle of the diaphragm  264 , and less thickness at the outer perimeter (periphery) of the diaphragm  264 . The diaphragm  264  is referred to “non-uniform diaphragm” due to the fact that thickness of the diaphragm  264  is greatest at geometric center of the diaphragm  264 , and because the thickness is non-consistent throughout the diaphragm  264  is sometimes referred herein as a “centralized non-uniform diaphragm” or, more simply, as an “non-uniform diaphragm.” 
     As shown in  FIG.  2 B , the non-uniform diaphragm  264  may be described as having a total area  283 , where a portion of the total area  283  is formed by the central region  280  and a portion of the total area  283  is formed by the peripheral region  282 . It is to be appreciate that the size of the central region  280  relative to the size of the total area  283  and the size of the peripheral region  282  may vary in different embodiments presented herein. In certain examples, the central region  280  may form at least approximately fifty (50) percent (%) of the total area  283  of the diaphragm  264 . In further examples, the central region  280  may form at least approximately 50% of the total area  283  of the diaphragm  264 , but less than approximately seventy-five (75)% of the total area  282  of the diaphragm  264 . 
     In accordance with certain embodiments presented herein, the central region  280  and the peripheral region  282  are unitary/integrated and formed from the same material. For example, the central region  280  and the peripheral region  282  may each be made from titanium, a titanium alloy, or another biocompatible materials configured to hermetically seal end  262  of the housing  262  and to vibrate in response to movement of coupling member  266 . 
     In certain embodiments in which the central region  280  and the peripheral region  282  are unitary, the non-uniform diaphragm  264  may be formed using a laser micro-machining process where material is removed to form the thinner regions/sections of the non-uniform diaphragm  264  (e.g., start with a cylinder-shaped piece of material and remove portions around the outer edge to form the thinner peripheral region). In other embodiments in which the central region  280  and the peripheral region  282  are unitary, the non-uniform diaphragm  264  may be formed using a surface deposition process where material is added to form the thicker central region (e.g., start with a planar/flat membrane and add/deposit material on the surface thereof to form the thicker central region). 
     In other embodiments, the central region  280  and the peripheral region  282  may be separate components that are attached to one another. For example, the peripheral region  282  could be formed as a planar membrane and the central region  280  could be attached to the surface thereof (e.g., via welding, using an adhesive, etc.). 
     As described further below, the increased thickness of the central region  280 , relative to the thickness of the peripheral region  282 , results in mechanics (mechanical operation) for the non-uniform diaphragm  264  that are significantly different than those of conventional diaphragms that have a substantially constant thickness, particularly when coupled to a vibrating structure of a recipient’s body. This is illustrated with reference to  FIGS.  3 A- 3 C  and  FIGS.  4 A- 4 C , where  FIGS.  3 A- 3 C  are schematic cross-sectional diagrams illustrating operation of a conventional diaphragm of an implantable sound sensor, while  FIGS.  4 A- 4 C  are simplified schematic diagrams illustration operation of a non-uniform diaphragm of an implantable sound sensor, in accordance with embodiments presented herein. 
     Referring first to  FIG.  3 A , shown is a simplified cross-sectional view of a conventional diaphragm  357  mechanically attached to a housing  362  and to a coupling member  366 . The coupling member  366  mechanically couples the diaphragm  357  to a vibrating structure (not shown in  FIGS.  3 A- 3 C ) of a recipient. The diaphragm  357  is shown in  FIG.  3 A  at a resting or default position, there the diaphragm  357  is substantially in-line with a reference axis  355 . 
     In operation, the vibrating structure vibrates in response to an acoustic signal (sound wave) received via the recipient’s outer ear. This vibration of the vibrating structure imparts vibration to the coupling member  366  which, in turn, imparts vibration to the diaphragm  357  along a vibrational axis  369 . The vibration of the diaphragm  357  is shown in  FIGS.  3 B and  3 C  by arrows  371 A and  371 B, respectively. That is, as shown by arrow  371 A, the diaphragm  357  will deform/deflect into a vibration chamber  376  that exists between the diaphragm  357  and a vibration sensor (not shown in  FIGS.  3 A- 3 C ) and, as shown by arrow  371 B, the diaphragm  357  will deform/deflect away from the chamber  376  of the housing  362 . This vibration of the diaphragm  357  causes movement/displacement of the contents (e.g., gas or liquid) of the vibration chamber  376 . 
     Due to the mechanical attachment of the coupling member  366  to the diaphragm  357 , and due to the uniform thickness of the diaphragm  357 , the maximum displacement of the diaphragm  357  is localized to the relatively small area where the coupling member  366  is attached to the diaphragm  357 . That is, as shown in  FIGS.  3 B and  3 C , maximum displacement occurs only at the area of the diaphragm  357  that is localized to the vibrational axis  369  (i.e., only the area at which the diaphragm  357  is physically attached to the coupling member  366 ). The amount of displacement then decreases in a substantially uniform manner as a function of lateral distance from the vibrational axis  369 . For ease of description, this type of conventional diaphragm displacement shown in  FIGS.  3 B and  3 C  is referred to herein as “localized” maximum displacement. 
     The result of the localized maximum displacement of diaphragm  357  is, as shown in  FIG.  3 B , a first displacement volume (V 1A ) in the direction of  371 A, and, as shown in  FIG.  3 C , a second displacement volume (V 1B ) in the direction of  371 B. The displacement volumes V 1A  and V 1B  refer the volume of the contents of chamber  376  that is displaced at the point of maximum displacement of the diaphragm  357 , in directions  371 A and  371 B, respectively, for a given acoustic signal (sound wave) received at (i.e., impinging on) the vibrating structure. These displacement volumes V 1A  and V 1B  are what is detected by the vibration sensor within the housing  362 . 
     Referring next to  FIG.  4 A , shown is a simplified cross-sectional view of a non-uniform diaphragm  464  in accordance with embodiments presented herein. In the examples of  FIGS.  4 A- 4 C , the non-uniform diaphragm  464  has the same general arrangement as non-uniform diaphragm  264  of  FIGS.  2 A- 2 C . In particular, non-uniform diaphragm  464  is comprised of a central region  480  having a first thickness (D 1 ) and a peripheral region  482  having a second thickness (D 2 ) that is less than the first thickness of central region  480 . The central region  480  has a general cylindrical shape, and the peripheral region  482  comprises a ring-shape surrounding the central region  480  (i.e., extending around the outer edge of the central region  480 ). That is, diaphragm  464  has a greater thickness in the geometric center/middle of the diaphragm  464 , and less thickness at the outer perimeter (periphery) of the diaphragm  464 . 
     As shown, the non-uniform diaphragm  464  is mechanically attached to a housing  462  and to a coupling member  466 . The coupling member  466  mechanically couples the diaphragm  464  to a vibrating structure (not shown in  FIGS.  4 A- 4 C ) of a recipient. The diaphragm  464  is shown in  FIG.  4 A  at a resting or default position, there the diaphragm  464  is substantially in-line with a reference axis  455 . 
     In operation, the vibrating structure vibrates in response to an acoustic signal (sound wave) received via the recipient’s outer ear. This vibration of the vibrating structure imparts vibration to the coupling member  466  which, in turn, imparts vibration to the non-uniform diaphragm  464  along a vibrational axis  469 . The vibration of the non-uniform diaphragm  464  is shown in  FIGS.  4 B and  4 C  by arrows  471 A and  471 B, respectively. That is, as shown by arrow  471 A, the non-uniform diaphragm  464  will deform/deflect into a vibration chamber  476  that exists between the non-uniform diaphragm  464  and a vibration sensor (not shown in  FIGS.  4 A- 4 C ) and, as shown by arrow  471 B, the non-uniform diaphragm  464  will deform/deflect away from the vibration chamber  476  of the housing  462 . This vibration of the non-uniform diaphragm  464  causes movement/displacement of the contents (e.g., gas or liquid) of vibration chamber  476 . 
     As noted above with reference to  FIGS.  3 A- 3 C , with conventional diaphragms having a uniform thickness, mechanically coupled vibration causes maximum displacement of the conventional diaphragm only at the area of the diaphragm that is localized to the vibrational axis. However, as shown in  FIGS.  4 B and  4 C , the mechanical properties of non-uniform diaphragms presented herein, such as non-uniform diaphragm  464 , result in a significantly different (i.e., increased) area of maximum displacement. More particularly, due to the mechanical attachment of the coupling member  466  to the diaphragm  464 , and due to the non-uniform thickness of the diaphragm  464 , the maximum displacement of the diaphragm  464  occurs generally across the substantial entirety of the central region  480 . The amount of displacement then beings to decrease at the junction of the central region  480  and the peripheral region  482  (i.e., in the area of the diaphragm that transitions from thicker to thinner). The displacement then decreases across peripheral region  482 , in a substantially uniform manner as a function of lateral distance from the vibrational axis  469 . Stated differently, the greater thickness of the central region  480  relative to the peripheral region  482  causes the substantial entirety of the central region  480  (i.e., substantially all of the thicker section) to move in response to the vibration from the coupling element  466 , while the peripheral region  482  deforms. For ease of description, this type of diaphragm displacement shown in  FIGS.  4 B and  4 C  is referred to herein as “distributed” maximum displacement. 
     As noted above, the size of a central region of a non-uniform diaphragm may vary in different embodiments presented herein. For example, the central region  480  of non-uniform diaphragm  464  may form at least approximately 50% of the total area of the diaphragm  464 . Therefore, in such embodiments, at least approximately 50% of the diaphragm  464  reaches maximum displacement in response to a given acoustic signal. 
     The result of the distributed maximum displacement of diaphragm  464  is, as shown in  FIG.  4 B , a first displacement volume (V 2A ) in the direction of  471 A, and, as shown in  FIG.  4 C , a second displacement volume (V 2B ) in the direction of  471 B. The displacement volumes V 2A  and V 2B  refer the volume of the contents of chamber  476  that is displaced at the point of maximum displacement of the diaphragm  464 , in directions  471 A and  471 B, respectively, for a given acoustic signal received at the vibrating structure. These displacement volumes V 2A  and V 2B  are what is detected by the vibration sensor within the housing  462 . 
     In general, if diaphragms  357  and  464  have the same outer dimension (e.g., diameter), coupled to the same vibrating structure by the same coupling member, the same acoustic signal will cause the diaphragm  464  to displace more content of the corresponding vibration chamber. That is, in this scenario (i.e., same acoustic signal, same vibrating structure, and same coupling), V 2A  is greater than V 1A  and V 2B  is greater than V 1B . The increased displacement volumes generated by non-uniform diaphragm  464 , relative to the conventional diaphragms, means that non-uniform diaphragm  464 , and the associated implantable sound sensor, become more sensitive to acoustic signals impinging upon the vibrating structure (i.e., more contents of the chamber is moved for the same acoustic signal in the embodiments presented). 
     As detailed above, in accordance with embodiments presented herein, the thickness of certain portions of the non-uniform diaphragms are increased in order to increase the overall sensitivity of the implantable sound sensor. That is, by changing the thickness, and thus stiffness, in the middle of the diaphragm, the techniques presented herein increase the sensitivity while keeping the same overall diameter when used with a mechanical coupling to vibrating structure of a recipient’s anatomy (i.e., the microphone becomes more sensitive for the same form factor). Generally speaking, it is counter intuitive that a thicker diaphragm would provide increased sensitivity and provide better sound performance, as is the case with the non-uniform diaphragms presented herein. Instead, conventional thinking is that microphone sensitivity can be increased by increasing the diameter (i.e., total area) of the diaphragm and/or by reducing the thickness of the diaphragm (i.e., traditionally, the goal has been to make diaphragms as thin as possible so that they are most responsive). 
       FIGS.  2 A and  2 B , as well as  FIGS.  4 A- 4 C  have been described with reference to one specific arrangement for a non-uniform diaphragm. However, it is to be appreciated that non-uniform diaphragms in accordance with embodiments presented herein may have a number of other physical arrangements that provide the non-uniform diaphragm with similar mechanics to that described with reference to  FIGS.  4 A- 4 C . Examples of such other suitable arrangements are shown in  FIGS.  5 - 21   . In each of  FIGS.  5 - 21   , the corresponding non-uniform diaphragms is comprised of a central region having a first thickness (D 1 ) and a peripheral region having a second thickness that is less than the first thickness of central region so as to operate in a similar manner as described above with reference to  FIGS.  4 A- 4 C . 
     Referring first to  FIG.  5   , shown is a non-uniform diaphragm  564  in accordance with embodiments presented herein coupled to a coupling member  566 . In the example of  FIG.  5   , the non-uniform diaphragm  564  is comprised of a central region  580  and a peripheral region  582 . The central region  580  has a general cylindrical shape, while the peripheral region  582  comprises a ring-shape surrounding the central region  580  (i.e., extending around the outer edge of the central region  580 ). Although the peripheral region  582  has a general ring shape, it also has an undulating or ridged cross-sectional shape (i.e., has undulating or ridged inner and outer surfaces  581 A and  581 B, respectively). That is, in contrast of  FIGS.  2 B and  4 A- 4 C  where the peripheral region regions are generally planar members, the peripheral region  582  is an undulating member. 
     Referring next to  FIG.  6   , shown is a non-uniform diaphragm  664  in accordance with embodiments presented herein coupled to a coupling member  666 . In the example of  FIG.  6   , the non-uniform diaphragm  664  is comprised of a central region  680  and a peripheral region  682 . The central region  680  has a general cylindrical shape, while the peripheral region  682  comprises a ring-shape surrounding the central region  680  (i.e., extending around the outer edge of the central region  680 ). 
     In the examples of  FIGS.  2 B and  4 A- 4 C , the corresponding cylindrical central regions were positioned at the inner surface of the diaphragms (i.e., the central regions extended into the vibration chamber of the implantable sound sensor). In the example of  FIG.  6   , the central region  680  is positioned at the outer surface of the diaphragm  664  (i.e., the central region  680  extends away from the vibration chamber of the implantable sound sensor). 
     Referring next to  FIG.  7   , shown is a non-uniform diaphragm  764  in accordance with embodiments presented herein coupled to a coupling member  766 . In the example of  FIG.  7   , the non-uniform diaphragm  764  is comprised of a central region  780  and a peripheral region  782 . The central region  780  has a general cylindrical shape, while the peripheral region  782  comprises a ring-shape surrounding the central region  780  (i.e., extending around the outer edge of the central region  780 ). 
     In the examples of  FIGS.  2 B and  4 A- 4 C , the corresponding cylindrical central regions were positioned at the inner surface of the diaphragms (i.e., the central regions extended into the vibration chamber of the implantable sound sensor). In the example of  FIG.  7   , the central region  780  is positioned at both the outer surface of the diaphragm  764 , as well as the inner surface of the diaphragm  764 . Stated differently, the central region  780  has a first portion  780 A that extends into the vibration chamber of the implantable sound sensor, and a second portion  780 B that extends away from the vibration chamber of the implantable sound sensor). 
     Referring next to  FIG.  8   , shown is a non-uniform diaphragm  864  in accordance with embodiments presented herein coupled to a coupling member  866 . In the example of  FIG.  8   , the non-uniform diaphragm  864  is comprised of a central region  880  and a peripheral region  882 . The central region  880  has a general conical shape, while the peripheral region  882  comprises a ring-shape surrounding the central region  880  (i.e., extending around the outer edge of the central region  880 ). 
     Referring next to  FIG.  9   , shown is a non-uniform diaphragm  964  in accordance with embodiments presented herein coupled to a coupling member  966 . In the example of  FIG.  9   , the non-uniform diaphragm  964  is comprised of a central region  980  and a peripheral region  982 . The central region  980  has a general conical shape, while the peripheral region  982  comprises a ring-shape surrounding the central region  980  (i.e., extending around the outer edge of the central region  980 ). 
     In the example of  FIG.  8   , the conical central region  880  is positioned at the outer surface of the diaphragm  864  (i.e., the central region  880  extends away from the vibration chamber of the implantable sound sensor). In the example of  FIG.  9   , the central region  980  is positioned at the inner surface of the diaphragm  964  (i.e., the central region  680  extends into the vibration chamber of the implantable sound sensor). 
     Referring next to  FIG.  10   , shown is a non-uniform diaphragm  1064  in accordance with embodiments presented herein coupled to a coupling member  1066 . In the example of  FIG.  10   , the non-uniform diaphragm  1064  is comprised of a central region  1080  and a peripheral region  1082 . The peripheral region  1082  comprises a ring-shape surrounding the central region  1080  (i.e., extending around the outer edge of the central region  1080 ). In the example of  FIG.  10   , the central region  1080  is positioned at both the outer surface of the diaphragm  1064 , as well as the inner surface of the diaphragm  1064 . Stated differently, the central region  1080  has a first conical portion  1080 A that extends into the vibration chamber of the implantable sound sensor, and a second conical portion  1080 B that extends away from the vibration chamber of the implantable sound sensor). 
     Referring next to  FIG.  11   , shown is a non-uniform diaphragm  1164  in accordance with embodiments presented herein coupled to a coupling member  1166 . In the example of  FIG.  11   , the non-uniform diaphragm  1164  is comprised of a central region  1180  and a peripheral region  1182 . The central region  1180  has an elongated conical shape, where the surfaces of the cone is defined by a non-liner curvature. The peripheral region  1182  comprises a ring-shape surrounding the central region  1180  (i.e., extending around the outer edge of the central region  1180 ). 
     Referring next to  FIG.  12   , shown is a non-uniform diaphragm  1264  in accordance with embodiments presented herein coupled to a coupling member  1266 . In the example of  FIG.  12   , the non-uniform diaphragm  1264  is comprised of a central region  1280  and a peripheral region  1282 . The central region  1280  has a general flattened-conical shape, while the peripheral region  1282  comprises a ring-shape surrounding the central region  1280  (i.e., extending around the outer edge of the central region  1280 ). 
     Referring next to  FIG.  13   , shown is a non-uniform diaphragm  1364  in accordance with embodiments presented herein coupled to a coupling member  1366 . In the example of  FIG.  13   , the non-uniform diaphragm  1364  is comprised of a central region  1380  and a peripheral region  1382 . The central region  1380  has a general tetrahedron or hemispherical shape, while the peripheral region  1382  comprises a ring-shape surrounding the central region  1380  (i.e., extending around the outer edge of the central region  1380 ). Referring next to  FIG.  14   , shown is a non-uniform diaphragm  1464  in accordance with embodiments presented herein coupled to a coupling member  1466 . In the example of  FIG.  14   , the non-uniform diaphragm  1464  is comprised of a central region  1480  and a peripheral region  1482 . The central region  1480  has a general paraboloid or parabolic shape, while the peripheral region  1482  comprises a ring-shape surrounding the central region  1480  (i.e., extending around the outer edge of the central region  1480 ). 
     In general,  FIGS.  5 - 14    illustrate non-uniform diaphragms having central regions each defined by a substantially-circular bases, where the peripheral region has a ring-shape surrounding the circular base of the central region. It is to be appreciated that the use of central regions having substantially-circular bases is illustrative and that other shapes are possible. For example,  FIG.  15    is a top-view of a non-uniform diaphragm  1564  in accordance with embodiments presented herein having a central region  1580  and a peripheral region  1582 . In this embodiment, the central region  1580  is defined by a substantially-square base  1587 . 
     As another example,  FIG.  16    is a top-view of a non-uniform diaphragm  1664  in accordance with embodiments presented herein having a central region  1680  and a peripheral region  1682 . In this embodiment, the central region  1680  is defined by a substantially-triangular base  1687 . 
     It is to be appreciated that, in certain embodiments presented herein, a central region of a non-uniform diaphragm may include one or more holes or cut-outs that may, for example, reduce weight of the central region relative to substantially solid central regions.  FIGS.  17 - 19    are top views of non-uniform diaphragms that include cut-outs in the central regions thereof. 
     More specifically, first to  FIG.  17   , shown is a non-uniform diaphragm  1764  comprising a central region  1780  and a peripheral region  1782 . In this example, the central region  1780  comprises a plurality of elongate cut-outs  1786  extending outward from a center  1788  of the central region  1780 . In this example, the cut-outs  1786  terminate prior to outer edge  1789  of the central region  1780 . 
     Referring next to  FIG.  18   , shown is a non-uniform diaphragm  1864  comprising a central region  1880  and a peripheral region  1882 . In this example, the central region  1880  comprises a plurality of elongate cut-outs  1886  extending outward from a center  1888  of the central region  1880 . In this example, the cut-outs  1886  extend to the outer edge  1889  of the central region  1880 . Stated differently, the central region  1880  comprises a plurality of arms  1890  extending from the center  1888  thereof. 
     Referring next to  FIG.  19   , shown is a non-uniform diaphragm  1964  comprising a central region  1980  and a peripheral region  1982 . In this example, the central region  1980  comprises a plurality of cylindrical channels  1986  extending longitudinally through the central region  1980 . 
     As described above,  FIG.  5   , illustrates a non-uniform diaphragm  564  in accordance with embodiments presented herein that comprises a peripheral region  582  having an undulating or ridged cross-sectional shape (i.e., has undulating or ridged inner and outer surfaces  581 A and  581 B, respectively). That is,  FIG.  5    illustrates an embodiment in which the peripheral region  582  is an undulating member. 
     In  FIG.  5   , the undulating peripheral region  582  is substantially co-planar with the central region  580 . It is to be appreciate that this co-planar arrangement of the undulating peripheral region  582  and the central region  580  is illustrative and that other arrangements may be used in embodiments presented herein. For example,  FIG.  20    illustrates an embodiment of a non-uniform diaphragm  2064  in accordance with embodiments presented herein that comprises a central region  2080  and a peripheral region  2082  having an undulating or ridged cross-sectional shape. However, in this example, the peripheral region  2082  is substantially orthogonal to central region  2080  (i.e., the central region  2080  and peripheral region  2082  are not co-planar). 
       FIG.  21    illustrates another embodiment of a non-uniform diaphragm  2264  in accordance with embodiments presented herein that comprises a central region  2280  and a peripheral region  2082  having an undulating or ridged cross-sectional shape. However, in this example, the peripheral region  2282  is substantially parallel to a central region  2180  (i.e., the central region  2180  and peripheral region  2182  are positioned in substantially parallel planes). As shown in  FIG.  21   , the peripheral region  2182  is mechanically attached to the central region  2180  via a spacing element  2191 . In certain embodiments, central region  2180 , peripheral region  2182 , and spacing element  2191  may be a unitary structure formed from the same material. In other embodiments, one or more of central region  2180 , peripheral region  2182 , and spacing element  2191  may be a discrete component that is joined to one or more of the other elements (e.g., via welding). 
     It is to be appreciated that the above described embodiments are not mutually exclusive and that the various embodiments can be combined in various manners and arrangements. 
     The invention described and claimed herein is not to be limited in scope by the specific preferred embodiments herein disclosed, since these embodiments are intended as illustrations, and not limitations, of several aspects of the invention. Any equivalent embodiments are intended to be within the scope of this invention. Indeed, various modifications of the invention in addition to those shown and described herein will become apparent to those skilled in the art from the foregoing description. Such modifications are also intended to fall within the scope of the appended claims.