Patent Publication Number: US-2009240099-A1

Title: Bi-modal cochlea stimulation

Description:
RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Application Ser. No. 61/032,812, filed on Feb. 29, 2008, entitled “BI-MODAL COCHLEA STIMULATION”, the entirety of which is hereby incorporated by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to implantable hearing instruments, and more particularly, to a bi-modal, implantable hearing instrument adapted for mechanical and electrical stimulation of the cochlea. 
     BACKGROUND OF THE INVENTION 
     The utilization of implanted hearing instruments is ever-increasing. In this regard, implantable hearing instruments provide operative and cosmetic advantages relative to conventional ear canal hearing instruments. 
     Typically, an implanted hearing instrument may comprise implanted componentry for mechanically stimulating a middle ear component of a patient&#39;s auditory system, or alternatively, for electrically stimulating an inner ear component of a patient&#39;s auditory system. As may be appreciated, depending on patient-specific needs, both approaches have relative advantages and disadvantages. Further, in either approach the implantation of componentry entails a surgical procedure with attendant surgical personnel and facility requirements. 
     To facilitate increased utilization of implanted hearing instruments, the present inventor has recognized the desirability of providing an approach which realizes the benefits of both mechanical stimulation and electrical stimulation of a patient&#39;s auditory system, and which also facilitates the efficient and reliable surgical positioning of implantable hearing instrument componentry. 
     SUMMARY OF THE INVENTION 
     An implantable hearing instrument comprising the present invention may include a transducer for providing a vibratory output (e.g. in response to a first electrical drive signal corresponding with an acoustic signal), and a supply electrode for providing an electrical output (e.g. in response to a second electrical drive signal corresponding with the acoustic signal). The vibratory output of the transducer is employable for direct mechanical stimulation of a patient&#39;s cochlea, and the electrical output of the supply electrode is employable for direct electrical stimulation of a patient&#39;s cochlea, wherein enhanced bi-modal cochlea stimulation may be realized. 
     For example, enhanced perception of acoustic signals, or hearing assistance, may be achieved over a relatively wide acoustic frequency range. Additionally, or alternatively, enhanced bi-modal stimulation may be realized to lessen patient discomfort associated with tinnitus via enhanced “masking”. In this regard, the apparatus and methods of the present invention are employable to realize enhanced hearing assistance and/or tinnitus treatment. 
     In one aspect, the transducer may be an electromechanical transducer, and the supply electrode may be supportably interconnected to or otherwise in vibratory engagement with the electromechanical transducer. In this regard, the electromechanical transducer may comprise a housing and a vibratory member that is supportably interconnected to the housing for movement relative thereto to communicate the vibratory output. In turn, the supply electrode may be supportably interconnected to, defined by or in vibratory engagement with the vibratory member. 
     In one arrangement, the supply electrode may define a distal end for engaging a patient&#39;s cochlea, wherein both electrical stimulation and mechanical stimulation of a patient&#39;s cochlea are realized via the distal end. In one approach, the distal end may comprise an electrically-conductive material and may include an arcuate surface for engaging an outer surface of a patient&#39;s cochlea. By way of example, a bulbous surface may be sized and positioned to engage a round window membrane, oval window membrane, a bony exterior, a semicircular canal wall or artificial fenestration of a patient&#39;s cochlea. 
     In another approach, the distal end may be adapted for partial insertion into a patient&#39;s cochlea. For example, the distal end may be reduced in cross-section (e.g. tapered down) to facilitate penetration/insertion and advancement through a small surgical incision on a patient&#39;s cochlear component, e.g. an oval window membrane or round window membrane (e.g. wherein the supply electrode extends from outside to inside the cochlea). In this approach, a small amount of fascia or other autologous tissue may be disposed around the supply electrode to sealably interconnect the supply electrode to the surrounding cochlear tissue after surgical placement. Further, in this approach the electrode may take the form of a prosthetic piston and a proximal end of the supply electrode may include a bail for selective interconnection to a vibratory member either prior to or after surgical placement of the supply electrode. 
     In another arrangement, a supply electrode may include a distal end and a proximal portion supportably interconnected or having a bail for selective interconnection to a vibratory member. The proximal portion of the vibratory member may also be adapted (e.g. reduced in cross-section) for partial insertion into a patient&#39;s cochlea. For example, the proximal portion may be tapered down to facilitate penetration/insertion and advancement through a small incision on a patient&#39;s cochlear component, e.g. an oval window membrane or round window membrane (e.g. wherein the supply electrode extends from outside to inside the cochlea). Again, a small amount of fascia or other autologous tissue may be disposed around the supply electrode to sealably interconnect the supply electrode to the surrounding oval window or round window tissue after surgical placement. The distal portion of the supply electrode may be flexible, jointed and/or otherwise curved for inserted positioning within a curved portion of a patient&#39;s cochlea. Further, the distal portion of the supply electrode may comprise a plurality of electrode elements spaced along the distal portion. In this regard, the drive signal supplied to the supply electrode may be provided to drive the plurality of electrode elements to affect electrical stimulation across a corresponding plurality of different frequency ranges. 
     In another aspect, an implantable hearing instrument may comprise a mounting member that is interconnectable in fixed relation to a patient&#39;s skull, and that is otherwise adapted for supportable interconnection of an electromechanical transducer thereto. Further, the instrument may include a positioning means, interconnectable between the electromechanical transducer and mounting member, for selectively locating the electromechanical transducer, vibratory member and supply electrode in a desired fixed position relative to a patient&#39;s cochlea. 
     In another aspect, the implantable hearing instrument may be provided so that vibratory output of the transducer mechanically stimulates a patient&#39;s cochlea across a first frequency range in response to the first electrical signal, and so that the supply electrode electrically stimulates a patient&#39;s cochlea across a second frequency range in response to the second electrical signal. In turn, the first and second frequency ranges may be established to be at least partially non-overlapping. In this regard, at least a portion of the first frequency range may comprise frequencies which are higher than those included in the second frequency range, and at least a portion of the second frequency range may include frequencies which are lower than those induced within the first frequency range. Further, in certain implementations, at least portions of the first and second frequency ranges may be provided to be overlapping. 
     In another aspect the transducer may include an external housing that defines a hermetically-sealed internal chamber therewithin, and an active transducer element located within the internal chamber for receiving the first electrical drive signal. Further, the supply electrode may be at least one of electrically interconnected to and defined by at least an electrically-conductive portion of the external housing. 
     In one approach, the transducer may comprise a floating mass transducer. In one implementation, the active element of the floating mass transducer may comprise a coil element fixedly interconnected to the housing. In another implementation, the active transducer element of the floating mass transducer may comprise a piezoelectric element. In both implementations, a mass may be disposed within the housing, wherein upon receipt of the first drive signal the active element moves relative to the mass causing the housing to vibrate. In turn, the housing may be disposed in physical contact with a patient&#39;s cochlea to yield mechanical stimulation. 
     In conjunction with the utilization of a floating mass transducer, the supply electrode may be defined by an electrically conductive portion of the external housing that is disposed to physically contact a patient&#39;s cochlea. In turn, the conductive portion of the housing may both electrically and mechanically stimulate a patient&#39;s cochlea. In a streamline arrangement, the external housing may be entirely electrically-conductive. In another approach, the transducer may comprise an electromechanical transducer having a vibratory member that is supportably interconnected to the external housing for movement relative thereto in response to the vibratory output. In this regard, the supply electrode may be supportably interconnected to the vibratory member. In one implementation, the supply electrode may define a distal end for engaging a patient&#39;s cochlea. For example, the distal end may be adapted for externally contacting the round window or oval window of a patient&#39;s cochlea. In another implementation, the distal end may be adapted for insertion through a patient&#39;s oval window or round window. 
     As may be appreciated, the present invention also comprises methods for stimulating a patient&#39;s cochlea with an implantable hearing instrument, wherein the methods include the steps of generating a vibratory output at a transducer to mechanically stimulate a patient&#39;s cochlea in response to a first electrical signal corresponding with an acoustic signal, and providing an electrical output at a supply electrode to electrically stimulate the patient&#39;s cochlea in response to a second electrical signal corresponding with the acoustic signal. The method may further comprise the step of applying the vibratory output directly to a patient&#39;s cochlea. Similarly, the providing step may include the further steps of directly engaging a patient&#39;s cochlea with a supply electrode, and conveying the second electrical signal to the supply electrode. 
     In one aspect, the applying step may comprise contacting a patient&#39;s cochlea with at least one of a vibratory member operatively interconnected to an electromechanical transducer and a supply electrode supportably carried by such a vibratory member. Such contact may be realized via a number of different approaches. 
     In one approach, the method may include inserting at least a distal portion of the at least one of the vibratory member and the supply electrode into a predetermined component of the patient&#39;s cochlea. In one implementation, the supply electrode may be supportably and distally mounted to a vibratory member, wherein the engaging step entails engagement of at least a portion of the supply electrode inside of the patient&#39;s cochlea. In another implementation, the supply electrode may be disposed to extend through and beyond a distal portion of the vibratory member, wherein a distal portion of the supply electrode is one of flexible, jointed and curved for positioning with a curved portion of a patient&#39;s cochlea. In yet another implementation, the supply electrode may be integrally defined by a vibratory member. 
     In another approach, the method may comprise engaging an external surface of a predetermined component of a patent&#39;s cochlea with at least one of a vibratory member and supply electrode. In one implementation, the supply electrode may be supportably and distally mounted to the vibratory member. In another approach, the supple electrode may be integrally defined by a vibratory member. 
     In another aspect, the vibratory output may be generated at a transducer having an external housing and an active transducer element located within an internal chamber of the external housing. In conjunction with this aspect, supply electro may be at least one of electrically connected to and defined by an electrically conductive portion of the external housing of the transducer. In one approach, the supply electrode may be defined by the electrically conductive portion of the external housing, wherein the engaging step includes contacting a patient&#39;s cochlea with the electrically conductive portion of the external housing. By way of example, the transducer may comprise a floating mass transducer, wherein the active transducer element is one of a coil element and a piezoelectric element. In turn, the floating mass transducer may include a mass, wherein the applying step includes moving the active transducer element relative to the mass to vibrate the external housing. 
     In another approach, the supply electrode may be supportably interconnected to and movable relative to an electromechanical transducer. In turn, the vibratory output may be applied to a patient&#39;s cochlea via said supply electrode. 
     Additional aspects and corresponding advantages of the present invention will become apparent to those skilled in the art upon consideration of the further descriptions that follow. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a fully implantable hearing instrument application comprising the present invention. 
         FIG. 2  illustrates one embodiment of a transducer and supportably interconnected, supply electrode employable in the application of  FIG. 1 . 
         FIG. 3  illustrates another embodiment of a transducer and supportably interconnected, supply electrode employable in the application of  FIG. 1 . 
         FIG. 4  is a side cross-sectional view of the embodiment of  FIG. 3 . 
         FIG. 5  illustrates yet another embodiment of a transducer and supportably interconnected, supply electrode employable in the application of  FIG. 1 . 
         FIG. 6  illustrates yet another embodiment of a transducer and supportably interconnected, supply electrode employable in the application of  FIG. 1 . 
         FIG. 7  illustrates a semi-implantable application comprising the present invention. 
         FIG. 8  illustrates a side cross-sectional view of one embodiment of an integrated transducer and supply electrode employable in the application of  FIG. 7 . 
         FIG. 9  illustrates a side cross-sectional view of another embodiment of an integrated transducer and supply electrode employable in the application of  FIG. 7 . 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  illustrates one application of the present invention. As illustrated, the application comprises a fully implantable hearing instrument system. As will be appreciated, the present invention may also be employed in conjunction with semi-implantable hearing instruments. In the embodiment shown, the ossicular chain has been removed for purposes of illustration. It should be appreciated, however, that the embodiment(s) described herein may also be employed with all or portions of the ossicular chain present. 
     In the illustrated system, a biocompatible implant housing  100  is located subcutaneously on a patient&#39;s skull. The implant housing  100  may include a signal receiver  118  (e.g., comprising a coil element) and a pendant microphone  130  that is positioned to receive acoustic signals through overlying tissue. The signal receiver  118  may be utilized for transcutaneously re-charging an energy storage device within the implant housing  100  (e.g. via inductive coupling with an external charging device), as well as for receiving program instructions for the hearing instrument system. 
     The implant housing  100  may be utilized to house a number of components of the fully implantable hearing instrument. For instance, the implant housing  100  may house an energy storage device (e.g. a rechargeable battery), a microphone  130 , and one or more signal processor(s). Various additional processing logic and/or circuitry components may also be included in the implant housing  100  as a matter of design choice. The signal processor(s) within the implant housing  100  may be electrically interconnected, e.g. via cable  106 , to a biocompatible electromechanical transducer  140  and to an electrical supply electrode  160  that may be supportably interconnected to, defined by a portion of and/or in vibratory engagement with the electromechanical transducer  140 , wherein the electromechanical transducer  140  may provide a vibratory output in response to a first electrical drive signal and the supply electrode  160  may provide an electrical output in response to a second electrical drive signal. In the later regard, the system may further include a return, or reference, electrode  102  positioned on the skull of a patient and electrically interconnected via electrical line  104  to circuitry within implant housing  100  used to generate the second drive signal. 
     The electromechanical transducer  140  may be supportably connected to a positioning system  110 , which in turn may be connected to a bone anchor  116  mounted within the patient&#39;s mastoid process (e.g., via a hole drilled through the skull). The transducer  140  may include a vibratory member  112  for operatively interfacing the transducer  140  with a cochlea  120  of the patient. In an operative state, the vibratory member  112  provides a communication path for vibratory output from the transducer  140  and mechanical stimulation of the cochlea  120 , e.g. through the transmission of vibrations to an oval window  122 , round window  124 , semicircular canal, bony exterior or an artificial fenestration of the patient&#39;s cochlea. As will be more fully discussed hereinbelow, the vibratory member  112  may also define, support and/or otherwise be in vibratory engagement with the supply electrode  160  for electrical stimulation of the cochlea  120 . 
     During normal operation, acoustic signals are received subcutaneously at the microphone  130 . Upon receipt of the acoustic signals, one or more signal processor(s) within the implant housing  100  processes the acoustic signals to provide processed electrical drive signals, e.g., a first drive signal to transducer  140  and a second drive signal to the supply electrode  160 . As will be appreciated, the signal processor(s) may utilize digital processing techniques to provide frequency shaping, amplification, compression, and other signal conditioning, including conditioning based on patient-specific fitting parameters. The first drive signal causes the vibratory member  112  of the transducer  140  to output mechanical vibrations at acoustic frequencies to effect the desired sound sensation via mechanical stimulation of the cochlea  120  at the oval window  122  or round window  124  of the patient. Further, the second drive signal causes the supply electrode  160  to provide an electrical output at acoustic frequencies to electrically stimulate the cochlea  120  at oval window  122  or round window  124  of the patient. 
     As may be appreciated, the first and second drive signals may be separately provided to mechanically and electrically stimulate the cochlea  120  across corresponding first and second predetermined frequency ranges, respectively. For example, the first and second predetermined frequency ranges may be at least partially non-overlapping, wherein the first frequency range includes lower frequencies not included in the second frequency range, and wherein the second frequency range includes higher frequencies not included within the first frequency range. Further, the first and second frequency ranges may be established to be partially overlapping. In one implementation, the first frequency range may be established to extend from about 20 Hz to 2000 Hz, and the second frequency range may be established to extend from about 1000 Hz to 10,000 Hz. 
     Reference is now made to  FIG. 2 , which illustrates an embodiment having an electrically conductive supply electrode  200  supportably interconnected to a vibratory member  112  of electromechanical transducer  140 . More particularly, the supply electrode  200  may comprise an electrically conductive, biocompatible material (e.g. titanium) that defines a distal end which is fixedly interconnected via an electrically non-conductive, biocompatible, intermediate member  210  (e.g. comprising a ceramic material) to vibratory member  112 . As illustrated via phantom lines in  FIG. 2 , the intermediate member  210  may comprise cup-shaped recesses at opposing ends to fixedly receive vibratory member  112  and supply electrode  200  therein. 
     As further illustrated, the supply electrode  200  may comprise an arcuate, or bulbous surface  202  for engaging a patient&#39;s cochlea  120 , e.g. the oval window  122 . Preferably, the supply electrode  200  may be positioned so that the arcuate surface  202  maintains contact with the patient&#39;s cochlea  120  during operations. For example, the supply electrode  200  may be implanted through a facial recess of the patient and brought into contact against the membrane of the round window  124 . Fascia may be interposed between the supply electrode  200  and membrane. In another approach, the supply electrode  200  may be provided on an elongated wire that defines or is interconnected to the vibratory member  112 . The supply electrode may be positioned and loaded against the oval window  122 , or alternatively, against a bony exterior of the cochlea, the cochlear semicircular canal, a fenestration in the oval window  122  or a piston prosthesis that has been inserted through a fenestration in the oval window  124 . 
     In this embodiment, cable  106  provides a first electrical drive signal to the electromechanical transducer  140  to affect vibrational output by vibratory member  112 . Cable  106  further provides a second electrical drive signal to supply electrode  200  to yield an electrical output (e.g. as illustrated in  FIG. 2  by a central phantom line that passes through vibratory member  112  and intermediate member  210  to contact supply electrode  200 ). 
     Reference is now made to  FIGS. 3 and 4  which illustrate an embodiment similar to that illustrated in  FIG. 2 , wherein common componentry is referenced utilizing the same reference numerals as utilized in relation to the embodiment of  FIG. 2 . In contrast to the  FIG. 2  embodiment, the embodiment of  FIGS. 3 and 4  includes a supply electrode  200  that is fixedly interconnected to vibratory member  112  via an electrically conductive intermediate member  212 . The vibratory member  112  is also electrically conductive, wherein the supply electrode  200  is electrically interconnected to an electrically conductive component of an external housing  220  comprising the electromechanically transducer  140 . In this regard, and referring particularly to  FIG. 4 , the transducer housing  220  may comprise an electrically conductive end member  222 . 
     Referring further to  FIG. 4 , in this embodiment the cable  106  includes a first electrical signal line  106   a  and a second electrical signal line  106   b  for conveying a first drive signal and second drive signal, respectively. The first signal line  106   a  is electrically interconnected via electrical lead  107  to an active element disposed within the housing  220 , and the second signal line  106   b  is electrically interconnected to the housing end member  222  for conveying the second drive signal to the supply electrode  200  via the electrically conductive vibratory member  112  and intermediate member  212 . 
     The end member  222  of housing  220  is interconnected to an electrically conductive cup member  224  with an electrically non-conductive member  226  interposed therebetween for isolation purposes. In turn, a hermetically sealed chamber  230  is defined within the housing  220 . The housing  220  houses a magnetic coil  210 , and stacked magnetic members  212 , each of which extend about a leaf member  214 , wherein the magnetic coil  210  and magnetic members  212  combinatively define active element that may be electrically driven to a generate a magnetic field to induce vibratory movement of the leaf member  214  at desired acoustic frequencies. In turn, the leaf member  214  may be interconnected to a drive pin  216 , as shown. 
     Further in this regard, the drive pin  216  may be disposed to pass through an electrically conductive first plug member  218  of the vibratory member  112  that is proximally interconnected to the end member  222  of transducer housing  220  (e.g., via laser welding to yield a hermetic seal), an electrically conductive bellows member  223  of the vibratory member  112  that is proximally interconnected to a distal end of the first plug member  218  (e.g., via laser welding to yield a hermetic seal), and an electrically conductive second plug member  224  of the vibratory member  112  that is proximally interconnected to a distal end of the bellows member  223  (e.g., via laser welding to yield a hermetic seal.) The second plug member  224  may be distally interconnected to a distal end of the drive pin  216  via an electrically non-conductive, intermediate plug member  226  (e.g., a ceramic member interconnected to yield a hermetic seal), wherein the second plug member  224  may be axially displaceable with but is electrically isolated from the drive pin  216 . In this regard the bellows member  223  may be provided with undulations that facilitate movement of drive pin  216  and the second plug member  224  relative to the transducer housing  220 , while allowing the first plug member  218  to maintain a fixed position relative to the transducer housing  220 . As shown, the intermediate member  212  may be interconnected to a distal end of the second plug member  224  and may include a slotted portion for receiving the supply electrode  200 . More particularly, the supply electrode  200  may be inserted into the slotted portion of the intermediate member  212 , wherein an outside surface of the slotted portion of the intermediate member  212  may be crimped to maintain the supply electrode  200  at desired fixed position relative to the intermediate member  212 . 
     As noted above, the electromechanical transducer  140  may be supportably interconnected to a positioning system  110  that is supportably interconnected to a mounting member, or bone anchor  116 . The bone anchor  116  may be of a type as taught in U.S. Pat. No. 6,293,903 entitled “APPARATUS AND METHOD FOR MOUNTING IMPLANTABLE HEARING AID DEVICE”, issued Sep. 25, 2001, the entirety of which is hereby incorporated by reference. Further, the positioning system  110  may be of the type as generally taught by U.S. Pat. No. 6,491,622 entitled “APPARATUS AND METHOD FOR POSITIONING AN IMPLANTABLE HEARING AID DEVICE” issued Dec. 10, 2002, the entirety of which is hereby incorporated by reference. 
     As best shown in  FIG. 4 , the positioning system  110  may include a carrier assembly  20  and a swivel assembly  40  that allow for selective three-dimensional positioning of the electromechanical transducer  140 , and interconnected vibratory member  112  and supply electrode  200 , at a desired location within a patient. In this regard, an external member  24  of the carrier assembly  20  may be supportively received and selectively secured in an opening defined through a split ball member  42  that is captured between plates  44  of the swivel assembly  40 . The interface between the carrier assembly  20  and swivel assembly  40  provides for pivotable, lateral positioning of the transducer  140 . That is, the carrier assembly  20  may pivot upon rotation of the ball member  42 , thereby allowing the vibratory member  112  and supply electrode  200  to be moved along an arcuate path to a desired position. In turn, the interconnected plates  44  may be selectively secured to a bone anchor  116  and clamped via a lock member  130  (shown in  FIG. 3 ) to compress the split ball member  42  and thereby maintain a selected pivotal orientation. At the same time, the carrier assembly  20  may be selectively secured along a continuum positions within the opening of the ball member  42 , thereby facilitating linear positioning of the interconnected transducer  140 , vibratory member  112  and supply electrode  200  in a depth dimension. Additionally, the carrier assembly  20  may be defined so that an internal member  22  thereof, connected to the transducer  140 , may be selectively advanced and retracted in the depth of dimension relative to an external member  24  (e.g., by utilizing a lead screw arrangement), thereby further facilitating selective linear positioning of the transducer  140 , vibratory member  112  and supply electrode  200 . 
     As may be appreciated, in relation to an implementation shown in  FIGS. 3 and 4 , the positioning system  110  may be employed to move (e.g., advance or retract) the distal end of supply electrode  200  toward a patient&#39;s cochlea  120  by moving the carrier assembly  20  relative to the swivel assembly  40 , by moving the internal member  22  of the carrier assembly  20  relative to the external member  24  thereof, and/or by pivoting the carrier assembly  20  relative to the swivel assembly  40  and mounting member  116 . 
     Reference is now made to  FIG. 5 , which illustrates another embodiment having a supply electrode  300  supportably interconnected to a vibratory member  112  of an electromechanical transducer  140 . In this embodiment, the supply electrode  300  is partially inserted and thereby positioned within a patient&#39;s cochlea  120 , e.g. through a small incision  330  in the membrane of the oval window  122  or round window  124 , or in the semicircular canal, bony exterior or an artificial fenestration of the patient&#39;s cochlea. For purposes of illustration in  FIG. 5 , a portion  350  of the oval window  122  is cut-away to show the internal positioning of the supply electrode  300 . The supply electrode  300  may comprise a surface  302  adapted to facilitate insertion into the oval window  122  of a patient. For example, the supply electrode  300  may comprise a tapered surface  302  that is advanced into the small incision  330  that is made through a patient&#39;s oval window  122  during implantation. As shown, fascia or other autologous tissue  340  has been introduced around the supply electrode  300  to facilitate sealing. 
     The supply electrode  300  may comprise an electrically conductive material that defines a distal end. The supply electrode  300  may be provided in the form of a separately positionable piston prosthesis with an end adapted to facilitate selective interconnection to a bail  114  provided at a distal end of the vibratory member  112 . 
     In this embodiment, cable  106  provides a first electrical drive signal to the electromechanical transducer  140  to affect vibrational output by vibratory member  112 . Additionally, a cable  108  may operatively interconnect the processor(s) of implant housing  100  to supply electrode  300  so as to provide a second electrical drive signal to supply electrode  300  to yield an electrical output. 
     As with the embodiments described in relation to  FIGS. 1-4 , transducer  140  may be supportably interconnected to a positioning system  110 . The positioning system may be supportably interconnected to a mounting member or bone anchor  116  and may otherwise be provided to facilitate selective positioning of the transducer  140  and supportably interconnected Vibratory member  112  and supply electrode  300 . 
     Reference is now made to  FIG. 6 , which illustrates another embodiment having a supply electrode  400  supportably interconnected to a vibratory member  112  of an electromechanical transducer  140 . In this embodiment, supply electrode  400  is partially positioned within a patient&#39;s cochlea  120  through a small incision  430  in the oval window  122  thereof, and for purposes of illustration, a portion  450  of the oval window  122  is cut-away to show the internal positioning of the supply electrode  400 . As shown, fascia or other autologous tissue  440  has been introduced around the supply electrode  400  to facilitate sealing. 
     The supply electrode  400  may comprise a proximal portion  401  and distal portion  403 . The distal portion  403  may be flexible, jointed or otherwise curved to facilitate insertion into a curved portion of a patient&#39;s cochlea  120 . The distal portion  403  may comprise a plurality of electrically-conductive electrode elements  405  disposed on a flexible member  404 . By way of example, electrode elements  405  may comprise 12 pairs of bipolar electrodes and/or 8 to 22 monopolar electrodes with a reference electrode. For a short insertion electrode, at least one of a set of 6 bipolar and a set of 6 monopolar electrodes with a reference electrode may also be of significant benefit. 
     As illustrated, the distal portion  403  is supportably interconnected to and extends away from the proximal portion  401 . In this regard, the proximal portion  401  may comprise an electrically non-conductive material. Further, the proximal portion  401  may comprise a distal end  402  having a reduced cross-section, e.g. a tapered surface  402  to facilitate insertion into the oval window  122  or round window  124  of a patient&#39;s cochlea  120 . The proximal portion  401  may be selectively interconnected to a bail  114  provided at a distal tip of the vibratory member  112 . 
     In this embodiment, cable  106  provides a first electrical drive signal to the electromechanical transducer  140  to affect vibrational output by vibratory member  112 . Additionally, cable  108  may operatively interconnect the processor(s) of implant housing  100  to supply electrode  400  so as to provide a second electrical drive signal to supply electrode  400  to yield an electrical output. 
     As with the embodiments described in relations to  FIGS. 1-5 , transducer  140  may be supportably interconnected to a positioning system  110 . The positioning system  110  may be supportably interconnected to a mounting member or bone anchor  116  and may otherwise be provided to facilitate selective positioning of the transducer  140  and supportably interconnected vibratory member  112  and supply electrode  400 . 
       FIG. 7  illustrates another application of the present invention. As illustrated, this application comprises a partially implantable hearing instrument system. As previously noted, the present invention may be employed in conjunction with partially implantable or fully-implantable hearing instruments. 
     In the illustrated system, a bio-compatible implant housing  500  is located subcutaneously on a patient&#39;s skull. The implant housing  500  includes a signal receiver (e.g. comprising a coil element) for transcutaneous receipt of wireless signals (e.g. radio frequency signals) from an external unit  501 . The external unit  501  may comprise a microphone for receiving acoustic signals, one or more signal processor(s) for processing electrical output signals from the microphone, and a coil for receiving processor signals and transcutaneous signal transmission to the implanted signal receiver (e.g. via inductive coupling). Additional external componentry may include a charging device for transcutaneously re-charging an implanted energy storage device (e.g. a rechargeable battery located within implant housing  100 ) via inductive coupling. The implant housing  500  may also include one or more signal processor(s) and associated circuitry that is electrically interconnected via cables  506 ,  508  to an integrated electrical and mechanical stimulation unit  540  attached to an oval window  122  of a patient. By way of example, the integrated unit  540  may be attached to the oval window  122  with an adhesive, glue, suture or the like. As will be further described, the integrated unit  540  is operable to provide a vibratory output and an electrical output directly to the cochlea of a patient. 
     In this regard, the integrated unit  540  may comprise a floating mass transducer for providing a vibratory output in response to a first electrical signal conveyed by cable  506 , wherein the integrated unit  540  includes an external housing  520  that defines a hermetically-sealed internal chamber therewithin, and an active transducer element located within the internal chamber for receiving the first electrical signal. Further, in the illustrated embodiment the external housing  520  may be electrically conductive to integrally define a supply electrode for providing an electrical output in response to a second electrical signal conveyed by cable  508 . In this regard, the system may further include a return or reference electrode  502  positionable on the skull of a patient and electrically interconnected via electrical line  504  to circuitry within implant housing  500  used to generate the second drive signal. 
     Reference is now made to  FIG. 8  which illustrates an embodiment of an integrated unit  540  having an integrated floating mass transducer and supply electrode. In this embodiment, the integrated unit  500  comprises a sealed, electrically conductive housing  520  that integrally defines a supply electrode and that houses a magnet assembly  512  and a coil  514 . The magnet assembly  512  may be loosely suspended within the housing  520 , and the coil  514  may be rigidly secured to the housing  520 . The magnet assembly  512  may include a permanent magnet  542  and associated pole pieces  544  and  546 . When a first electrical drive signal (e.g. an alternating current) is conducted to the coil  512  via electrical line  524  of cable  506 , the coil  512  and magnet assembly  514  oscillate relative to each other and cause the housing  520  to vibrate. In this regard, the coil  512  acts as the active element and magnet assembly  514  acts as the floating mass component of the transducer. 
     The exemplary housing  520  may be a cylindrical capsule having a diameter of 1 mm and a thickness of 1 mm, and may be made from an electrically conductive, biocompatible material such as titanium. The housing  520  may define first and second faces  532 ,  534  that are substantially parallel to one another, and an outer wall  523  which is substantially perpendicular to the faces  532 ,  534 . An electrically non-conductive interior wall  522  may be affixed to the interior of the housing  520  and may define a circular region which runs substantially parallel to the outer wall  523 . 
     The housing  520  may define a sealed chamber  530  having air spaces that surrounds the magnet assembly  512  so as to separate it from the interior of the housing  520  and allow it to oscillate freely without colliding with the coil  514  or housing  520 . The magnet assembly  512  may connected to the interior of the housing  520  by flexible membranes such as silicone buttons  560 . The magnet assembly  512  may alternatively be floated on a gelatinous medium such as silicon gel which fills the air spaces in the housing  520 . A substantially uniform flux field may be produced by configuring the magnet assembly  512  as shown in  FIG. 8 . In this regard, the assembly  512  may include a permanent magnet  542  positioned with ends  548 ,  550  containing the south and north poles substantially parallel to the circular faces  534 ,  532  of the housing  520 . A first cylindrical pole piece  544  may be connected to the end  548  containing the south pole of the magnet  542  and a second pole piece  546  may be connected to the end  550  containing the north pole. The first pole piece  544  may be oriented with its circular faces substantially parallel to the circular faces  532 ,  534  of the housing  520 . The second pole piece  546  has a circular face which has a rectangular cross-section and which may be located substantially parallel to the circular faces  532 ,  534  of the housing  520 . The second pole piece  546  may also comprise a pair of walls  554  which are parallel to the wall  523  of the housing  520  and which surrounds the first pole piece  544  and the permanent magnet  542 . 
     The coil  514  partially encircles the magnet assembly  512  and is fixed to the interior wall  522  of the housing  510  such that the coil  514  is more rigidly fixed to the housing  520  than the magnet assembly  512 . In one implementation, a pair of leads  524  of cable  506  are connected to the coil  514  and pass through an opening  526  in the housing  520  to the exterior of the housing  520 . The cable  506 , a first electrical drive signal, e.g. delivers an alternating current signal to the coil  514  via the leads  524 . The opening  526  is closed around the leads  524  to form a seal (not shown) which prevents contaminants from entering the housing  520 . As shown in  FIG. 8 , cable  508  may be physically interconnected to the electrically conductive housing  520 , wherein an electrical line  522  of cable  508  may convey a second electrical drive signal to the housing  520 . In turn, the housing  520  functions as the supply electrode to provide an electrical output for electrical stimulation of a patient&#39;s cochlea. 
     Reference is now made to  FIG. 9  which illustrates another embodiment of an integrated unit  640  having an integrated transducer and supply electrode. In this embodiment, a floating mass is caused to vibrate by a piezoelectric bimorph. More particularly, the integrated unit  640  comprises an electrically conductive housing  620  that integrally defines a supply electrode and that houses a bimorph assembly  604  and a driving weight  606  within an internal chamber  630 . One end of the bimorph assembly  604  may be secured to the inside of the housing  620  and may comprise a short piezoelectric strip  608  and a longer piezoelectric strip  610 . The two strips are oriented so that one strip contracts while the other expands when a voltage is applied across the strips via electrical leads  524  of cable  506 . 
     A driving weight  606  may be secured to one end of piezoelectric strip  610  (the “cantilever”). When a first drive signal (e.g. an alternating current) is conducted to the bimorph assembly  604  via leads  524 , the housing  620  and driving weight  600  oscillate relative to each other causing the housing  620  to vibrate. Preferably, the relative vibration of the housing  620  is substantially greater than the vibration of the driving weight  606 . 
     As shown in  FIG. 9 , cable  508  may be physically interconnected to the electrically conductive housing  620 , wherein an electrical line  527  of cable  508  may convey a second electrical drive signal to the housing  620 . In turn, the housing  620  functions as the supply electrode to provide an electrical output for electrical stimulation of a patient&#39;s cochlea. 
     The descriptions of the various embodiments hereinabove are for purposes of illustration and are not intended to limit the scope of the present invention. Various adaptations and modifications are intended to be with the scope of the present invention as defined by the claims which follow.