Abstract:
The present invention relates to a bone conduction device for enhancing the hearing of a recipient is provided. The bone conduction device may include a first sound input device configured to receive sound signals and generate a first electrical signal representative of the signal, a second sound input device configured to receive sound signals and generate a second electrical signal representative of the signal, electronic circuitry configured to select at least one of the first electrical signal and the second electrical signal, and an electronics module configured to generate a third electrical signal representing the sound signals based on at least of the first electrical signal and the second electrical signal.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application claims the benefit of U.S. Provisional Patent Application No. 61/041,185; filed Mar. 31, 2008, which is hereby incorporated by reference herein. 
     
    
     BACKGROUND 
       [0002]    1. Field of the Invention 
         [0003]    The present invention is generally directed to a bone conduction device, and more particularly, to a bone conduction device having a plurality of sound input devices. 
         [0004]    2. Related Art 
         [0005]    Hearing loss, which may be due to many different causes, is generally of two types, conductive or sensorineural. In many people who are profoundly deaf, the reason for their deafness is sensorineural hearing loss. This type of hearing loss is due to the absence or destruction of the hair cells in the cochlea which transduce acoustic signals into nerve impulses. Various prosthetic hearing implants have been developed to provide individuals who suffer from sensorineural hearing loss with the ability to perceive sound. One such prosthetic hearing implant is referred to as a cochlear implant. Cochlear implants use an electrode array implanted in the cochlea of a recipient to provide an electrical stimulus directly to the cochlea nerve, thereby causing a hearing sensation. 
         [0006]    Conductive hearing loss occurs when the normal mechanical pathways to provide sound to hair cells in the cochlea are impeded, for example, by damage to the ossicular chain or ear canal. Individuals who suffer from conductive hearing loss may still have some form of residual hearing because the hair cells in the cochlea are generally undamaged. 
         [0007]    Individuals who suffer from conductive hearing loss are typically not considered to be candidates for a cochlear implant due to the irreversible nature of the cochlear implant. Specifically, insertion of the electrode array into a recipient&#39;s cochlea results in the destruction of a majority of hair cells within the cochlea. This results in the loss of residual hearing by the recipient. 
         [0008]    Rather, individuals suffering from conductive hearing loss typically receive an acoustic hearing aid, referred to as a hearing aid herein. Hearing aids rely on principles of air conduction to transmit acoustic signals through the outer and middle ears to the cochlea. In particular, a hearing aid typically uses an arrangement positioned in the recipient&#39;s ear canal to amplify a sound received by the outer ear of the recipient. This amplified sound reaches the cochlea and causes motion of the cochlea fluid and stimulation of the cochlea hair cells. 
         [0009]    Unfortunately, not all individuals who suffer from conductive hearing loss are able to derive suitable benefit from hearing aids. For example, some individuals are prone to chronic inflammation or infection of the ear canal and cannot wear hearing aids. Other individuals have malformed or absent outer ear and/or ear canals as a result of a birth defect, or as a result of common medical conditions such as Treacher Collins syndrome or Microtia. Furthermore, hearing aids are typically unsuitable for individuals who suffer from single-sided deafness (total hearing loss only in one ear) or individuals who suffer from mixed hearing losses (i.e., combinations of sensorineural and conductive hearing loss). 
         [0010]    When an individual having fully functioning hearing receives an input sound, the sound is transmitted to the cochlea via two primary mechanisms: air conduction and bone conduction. As noted above, hearing aids rely primarily on the principles of air conduction. In contrast, other devices, referred to as bone conduction devices, rely predominantly on vibration of the bones of the recipients skull to provide acoustic signals to the cochlea. 
         [0011]    Those individuals who cannot derive suitable benefit from hearing aids may benefit from bone conduction devices. Bone conduction devices convert a received sound into a mechanical vibration representative of the received sound. This vibration is then transferred to the bone structure of the skull, causing vibration of the recipient&#39;s skull. This skull vibration results in motion of the fluid of the cochlea. Hair cells inside the cochlea are responsive to this motion of the cochlea fluid, generating nerve impulses resulting in the perception of the received sound. 
       SUMMARY 
       [0012]    In one aspect of the invention, a bone conduction device for enhancing the hearing of a recipient is provided. The bone conduction device comprises a first sound input device configured to receive acoustic sound signals and generate a first electrical signal representative of the acoustic signal, a second sound input device configured to receive acoustic sound signals and generate a second electrical signal representative of the acoustic signal, electronic circuitry configured to select at least one of the first electrical signal and the second electrical signal, and an electronics module configured to generate a third electrical signal representing the acoustic sound signals based on at least of the first electrical signal and the second electrical signal. 
         [0013]    In a second aspect of the present invention, a bone conduction device for enhancing the hearing of a recipient in provided. The bone conduction device, comprises a plurality of sound input elements, each sound input element configured to receive an acoustic sound signal and convert the acoustic signal into an electrical signal, resulting in a plurality of electrical signals, and a switching circuit configured to select at least one of the plurality of electrical signals based on the content of each of the plurality of electronic signals. 
         [0014]    In a third aspect of the present invention, a system for enhancing the hearing of a recipient through bone conduction for enhancing the hearing of a recipient in provided. The system comprises an abutment that it is attached to the recipient, the abutment having a recess thereon, a hearing device body portion, the hearing device body portion including, a first microphone configured to receive acoustic sound signals and generate a first electrical signal representative of the acoustic signal, a second microphone configured to receive acoustic sound signals and generate a second electrical signal representative of the acoustic signal, the first and second microphones being substantially equidistant from the longitudinal axis of the device, a switching device configured to select at least one of the first and second electrical signals, and an electronics module configured to generate a third electrical signal representing at least one of the first and second electrical signals, and a coupling member attached to the hearing device body portion, the coupling member having a protrusion thereon and configured to releasably couple to the abutment, wherein when the coupling device is coupled to the abutment, the protrusion engages the recess, thereby selecting one of the first microphone and the second microphones. 
         [0015]    Other objects, features and advantages of the present invention will become apparent to those skilled in the art from the following drawings and detailed description of the preferred embodiments. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0016]    Illustrative embodiments of the present invention are described herein with reference to the accompanying drawings, in which: 
           [0017]      FIG. 1  is a perspective view of an exemplary medical device, namely a bone conduction device, in which embodiments of the present invention may be advantageously implemented; 
           [0018]      FIG. 2A  is a high-level functional block diagram of a bone conduction device, such as the bone conduction device of  FIG. 1 , in accordance with an embodiment of the invention; 
           [0019]      FIG. 2B  is detailed functional block diagram of the bone conduction device illustrated in  FIG. 2A , in accordance with an embodiment of the invention; 
           [0020]      FIG. 3  is an exploded view of an embodiment of a bone conduction device in accordance with one embodiment of  FIG. 2B ; 
           [0021]      FIG. 4  is a view in section of a switching device for selection of a sound input device, in accordance with an embodiment of the invention; and 
           [0022]      FIG. 5  is a flowchart illustrating the conversion of an input sound into skull vibration, in accordance with an embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION  
       [0023]    Embodiments of the present invention are generally directed to a bone conduction device for converting a received sound signal into a mechanical force for delivery to a recipient&#39;s skull. The bone conduction device includes a plurality of sound input components, such as a plurality of microphones, to receive sound signals. The bone conduction device may then select from amongst these received sound signals or combine one or more of the sound signals. The resulting signal (e.g., the selected or combined signal) may then be provided to the recipient so that they may hear the sound corresponding to the resulting signal. 
         [0024]      FIG. 1  is a cross sectional view of a human ear and surrounding area, along with a side view of one of the embodiments of a bone conduction device  100 . In a fully functional human hearing anatomy, outer ear  101  comprises an auricle  105  and an ear canal  106 . A sound wave or acoustic pressure  107  is collected by auricle  105  and channeled into and through ear canal  106 . Disposed across the distal end of ear canal  106  is a tympanic membrane  104  which vibrates in response to acoustic wave  107 . This vibration is coupled to oval window or fenestra ovalis  110  through three bones of middle ear  102 , collectively referred to as the ossicles  111  and comprising the malleus  112 , the incus  113  and the stapes  114 . Bones  112 ,  113  and  114  of middle ear  102  serve to filter and amplify acoustic wave  107 , causing oval window  110  to articulate, or vibrate. Such vibration sets up waves of fluid motion within cochlea  115 . The motion, in turn, activates tiny hair cells (not shown) that line the inside of cochlea  115 . Activation of the hair cells causes appropriate nerve impulses to be transferred through the spiral ganglion cells and auditory nerve  116  to the brain (not shown), where they are perceived as sound. 
         [0025]      FIG. 1  also illustrates the positioning of bone conduction device  100  relative to outer ear  101 , middle ear  102  and inner ear  103  of a recipient of device  100 . As shown, bone conduction device  100  may be positioned behind outer ear  101  of the recipient; however it is noted that device  100  may be positioned in any suitable manner. 
         [0026]    In the embodiments illustrated in  FIG. 1 , bone conduction device  100  comprises a housing  125  having a plurality of microphones positioned therein or thereon (in this figure only one microphone  126  is visible). Housing  125  is coupled to the body of the recipient via coupling  140 . As described below, bone conduction device  100  may comprise a signal processor, a transducer, transducer drive components and/or various other electronic circuits/devices. 
         [0027]    In accordance with embodiments of the present invention, an anchor system (not shown) may be implanted in the recipient. As described below, the anchor system may be fixed to bone  136 . In various embodiments, the anchor system may be implanted under skin  132  within muscle  134  and/or fat  128  or the hearing device may be anchored in another suitable manner. In certain embodiments, a coupling  140  attaches device  100  to the anchor system. 
         [0028]    A functional block diagram of one embodiment of bone conduction device  100 , referred to as bone conduction device  200 , is shown in  FIG. 2A . In the illustrated embodiment, a sound  207  is received by sound input elements  202   a  and  202   b,  which may be, for example, microphones configured to receive sound  207 , and to convert sound  207  into an electrical signal  222 . Or, for example, one or more of the sound input elements  202   a  and  202   b  might be an interface that the recipient may connect to a sound source, such as for example a jack for receiving a plug that connects to a headphone jack of a portable music player (e.g., MP3 player) or cell phone. It should be noted that these are but some exemplary sound input elements, and the sound input elements may be any component or device capable of providing a signal regarding a sound. Although bone conduction device  200  is illustrated as including two sound input elements  202   a  and  202   b,  in other embodiments, bone conduction device  200  may comprise 3 or more sound input elements. 
         [0029]    As shown in  FIG. 2A , electrical signals  222   a  and  222   b  are output by sound input elements  202   a  and  202   b,  respectively, to a sound input element selection circuit  219  that selects the sound input element or elements to be used. Selection circuit  219  thus outputs a selected signal  221  that may be electrical signal  222   a,    222   b,  or a combination thereof As discussed below, the selection circuit  219  may select the electrical signal(s) based on, for example, input from the recipient, automatically via a switch, the environment, and/or a sensor in the device, or a combination thereof Additionally, in embodiments, the sound input elements  202  in addition to sending information regarding sound  207  may also transmit information indicative of the position of the sound input element  202  (e.g., its location in the bone conduction device  200 ) in electrical signal  222 . 
         [0030]    The selected signal  221  is output to an electronics module  204 . Electronics module  204  is configured to convert electrical signals  221  into an adjusted electrical signal  224 . Further, electronics module  204  may send control information via control signal  233  to the input selection circuit, such as, for example, information instructing which input sound element(s) should be used or information instructing the input selection circuit  219  to combine the signals  222   a  and  222   b  in a particular manner. It should be noted that although in  FIG. 2A , the electronics module  204  and input element selection circuit  219  are illustrated as separate functional blocks, in other embodiments, the electronics module  204  may include the input element selection circuit  219 . As described below in more detail, electronics module  204  may include a signal processor, control electronics, transducer drive components, and a variety of other elements. 
         [0031]    As shown in  FIG. 2A , a transducer  206  receives adjusted electrical signal  224  and generates a mechanical output force that is delivered to the skull of the recipient via an anchor system  208  coupled to bone conduction device  200 . Delivery of this output force causes one or more of motion or vibration of the recipient&#39;s skull, thereby activating the hair cells in the cochlea via cochlea fluid motion. 
         [0032]      FIG. 2A  also illustrates a power module  210 . Power module  210  provides electrical power to one or more components of bone conduction device  200 . For ease of illustration, power module  210  has been shown connected only to interface module  212  and electronics module  204 . However, it should be appreciated that power module  210  may be used to supply power to any electrically powered circuits/components of bone conduction device  200 . 
         [0033]    Bone conduction device  200  further includes an interface module  212  that allows the recipient to interact with device  200 . For example, interface module  212  may allow the recipient to adjust the volume, alter the speech processing strategies, power on/off the device, etc. Interface module  212  communicates with electronics module  204  via signal line  228 . 
         [0034]    In the embodiment illustrated in  FIG. 2A , sound input elements  202   a  and  202   b,  electronics module  204 , transducer  206 , power module  210  and interface module  212  have all been shown as integrated in a single housing, referred to as housing  225 . However, it should be appreciated that in certain embodiments, one or more of the illustrated components may be housed in separate or different housings. Similarly, it should also be appreciated that in such embodiments, direct connections between the various modules and devices are not necessary and that the components may communicate, for example, via wireless connections. 
         [0035]      FIG. 2B  provides a more detailed functional diagram of bone conduction device  200  of  FIG. 2A . In the illustrated embodiment, electronics module  204  comprises a sound or signal processor  240 , transducer drive components  242  and control electronics  246 . As explained above, in certain embodiments sound input elements  202   a  and  202   b  comprise microphones configured to convert a received acoustic signal into electrical signals  222   a  and  222   b.    
         [0036]    As illustrated in  FIG. 2B , electrical signals  222   a  and  222   b  are output from sound input elements  202   a  and  202   b  to sound input selection circuit  219 . The selection circuit may output electrical signal  221  to signal processor  240 . In one embodiment, the selection circuit is a two way switch that is activated by the recipient; however, it is noted that the selection switch may be any switch for operating a plurality of sound input elements, as discussed below. Further, selection circuit  219  may comprise a processor and other components, such that selection circuit  219  may implement a particular combination strategy for combining one or more signals from the sound input elements. 
         [0037]    Signal  221  may be signal  222   a,    222   b  or a combination thereof Signal processor  240  uses one or more of a plurality of techniques to selectively process, amplify and/or filter electrical signal  221  to generate a processed signal  226 . In certain embodiments, signal processor  240  may comprise substantially the same signal processor as is used in an air conduction hearing aid. In further embodiments, signal processor  240  comprises a digital signal processor. 
         [0038]    Processed signal  226  is provided to transducer drive components  242 . Transducer drive components  242  output a drive signal  224 , to transducer  206 . Based on drive signal  224 , transducer  206  provides an output force to the skull of the recipient. 
         [0039]    For ease of description the electrical signal supplied by transducer drive components  242  to transducer  206  has been referred to as drive signal  224 . However, it should be appreciated that processed signal  224  may comprise an unmodified version of processed signal  226 . 
         [0040]    As noted above, transducer  206  generates an output force to the skull of the recipient via anchor system  208 . As shown in  FIG. 2B , anchor system  208  comprises a coupling  260  and an implanted anchor  262 . Coupling  260  may be attached to one or more of transducer  206  or housing  225 . For example, in certain embodiments, coupling  260  is attached to transducer  206  and vibration is applied directly thereto. In other embodiments, coupling  260  is attached to housing  225  and vibration is applied from transducer  206  through housing  225 . 
         [0041]    As shown in  FIG. 2B , coupling  260  is coupled to an anchor implanted in the recipient, referred to as implanted anchor  262 . As explained with reference to  FIG. 3 , implanted anchor  262  provides an element that transfers the vibration from coupling  260  to the skull of the recipient. 
         [0042]    As noted above, a recipient may control various functions of the device via interface module  212 . Interface module  212  may include one or more components that allow the recipient to provide inputs to, or receive information from, elements of bone conduction device  200 , such, as for example, one or more buttons, dials, display screens, processors, interfaces, etc. 
         [0043]    As shown, control electronics  246  may be connected to one or more of interface module  212  via control line  228 , signal processor  240  via control line  232 , sound input selection circuit  219  via control line  233 , and/or transducer drive components  242  via control line  230 . In embodiments of the present invention, based on inputs received at interface module  212 , control electronics  246  may provide instructions to, or request information from, other components of bone conduction device  200 . In certain embodiments, in the absence of recipient inputs, control electronics  246  control the operation of bone conduction device  200 . 
         [0044]      FIG. 3  illustrates an exploded view of one embodiment of bone conduction device  200  of  FIGS. 2A and 2B , referred to herein as bone conduction device  300 . As shown, bone conduction device  300  comprises an embodiment of electronics module  204 , referred to as electronics module  304 . As illustrated, electronics module  304  includes a printed circuit board  314  (PCB) to electrically connect and mechanically support the components of electronics module  304 . Further, as explained above, electronics module  304  may also include a signal processor, transducer drive components and control electronics. For ease of illustration, these components have not been illustrated in  FIG. 3 . 
         [0045]    A plurality of sound input elements are attached to PCB  314 , shown as microphones  302   a  and  302   b  to receive a sound. As illustrated, the two microphones  302   a  and  302   b  are positioned equidistant or substantially equidistant from the longitudinal axis of the device; however, in other embodiments microphones  302   a  and  302   b  may be positioned in any suitable position. By being positioned equidistant or substantially equidistant from the longitudinal axis, bone conduction device  300  can be used on either side of a patient&#39;s head. The microphone facing the front of the recipient is generally chosen using the selection circuit as the operating microphone, so that sounds in front of the recipient can be heard; however, the microphone facing the rear of the recipient can be chosen, if desired. 
         [0046]    Bone conduction device  300  further comprises a battery shoe  310  for supplying power to components of device  300 . Battery shoe  310  may include one or more batteries. As shown, PCB  314  is attached to a connector  376  configured to mate with battery shoe  310 . Connector  376  and battery shoe  310  may be, for example, configured to releasably snap-lock to one another. Additionally, one or more battery connects (not shown) are disposed in connector  376  to electrically connect battery shoe  310  with electronics module  304 . 
         [0047]    In the embodiment illustrated in  FIG. 3 , bone conduction device  300  further includes a two-part housing  325 , comprising first housing portion  325   a  and second housing portion  325   b.  Housing portions  325  are configured to mate with one another to substantially seal bone conduction device  300 . 
         [0048]    In the embodiment of  FIG. 3 , first housing portion  325   a  includes an opening for receiving battery shoe  310 . This opening may be used to permit battery shoe  310  to inserted or removed by the recipient through the opening into/from connector  376 . Also in the illustrated embodiment, microphone covers  372  can be releasably attached to first housing portion  325   a.  Microphone covers  372  can provide a barrier over microphones  302  to protect microphones  302  from dust, dirt or other debris. 
         [0049]    Bone conduction device  300  further may include an embodiment of interface module  212 , referred to in  FIG. 3  as interface module  312 . Interface module  312  is configured to provide information or receive user input from the user. 
         [0050]    Also as shown in  FIG. 3 , bone conduction device  300  may comprise a transducer  206 , referred to as transducer  306 , and an anchor system  208 , referred to as anchor system  308  in  FIG. 3 . As noted above, transducer  306  may be used to generate an output force using anchor system  308  that causes movement of the cochlea fluid to enable sound to be perceived by the recipient. The output force may result in mechanical vibration of the recipient&#39;s skull, or in physical movement of the skull about the neck of the recipient. Anchor system  308  comprises a coupling  360  and implanted anchor  362 . Coupling  360  may be configured to attach to second housing portion  325   b.  As such, vibration from transducer  306  may be provided to coupling  360  through housing  325   b.  As illustrated, housing portion  325   b  may include an opening to allow a screw (not shown) to be inserted through opening  368  to attach transducer  306  to coupling  360 . In such embodiments, an O-ring  380  may be provided to seal opening  368  around the screw. 
         [0051]    As noted above, anchor system  308  includes implanted anchor  362 . Implanted anchor  362  comprises a bone screw  366  implanted in the skull of the recipient and an abutment  364 . In an implanted configuration, screw  366  protrudes from the recipient&#39;s skull through the skin. Abutment  364  is attached to screw  366  above the recipient&#39;s skin. In other embodiments, abutment  364  and screw  366  may be integrated into a single implantable component. Coupling  360  is configured to be releasably attached to abutment  364  to create a vibratory pathway between transducer  306  and the skull of the recipient. Using coupling  360 , the recipient may releasably detach the bone conduction device  300  from anchor system  308 . The user may then make adjustments to the bone conduction device  300  using interface module  312 , and when finished reattach the bone conduction device  300  to anchor system  308  using coupling  360 . A further description of exemplary user interface modules  312  and how they may be used by a user to view data or adjust control settings of the hearing device is provided in the U.S. patent application by John Parker, Christian Peclat, and Christoph Kissling entitled “A Bone Conduction Device with a User Interface,” filed concurrent with the present application, which is incorporated by reference herein in its entirety. 
         [0052]    As noted above, bone conduction device  300  may comprise two or more sound input elements, such as microphones  302   a  and  302   b.  Referring back to  FIG. 2B , these microphones may be represented as sound input elements  202   a  and  202   b.  Further, as previously noted, a selection circuit  219  may be used to select from different input elements  202   a  and  202   b  or combine the signals from the input elements  202   a  and  202   b  in some manner. In an embodiment the recipient may use a user interface  212  of the hearing device  200  to select from amongst the different input elements or direct the hearing device to implement a particular strategy to combine or select the signals from the input elements  202   a  and  202   b.    
         [0053]    One exemplary combining strategy is for the recipient, though the user interface, to selectively chose one of the microphones to function as a dominant microphone. If a microphone is selected to be the dominant microphone, then the signal processor may select and use the dominant signal and disregard the other signals in the event certain conditions arise, such as if the signal processor receives multiple noisy signals from each of the microphones and the signal processor is unable to determine which microphone signal includes the sound that would be of principal interest to the recipient. Similarly, in certain embodiments, the recipient may use the user interface to select an order of dominance for the microphones, such that, in noisy conditions, the signal processor first tries to decode the primary dominant microphone signal. If, however, the signal processor determines that this decoding fails to meet certain conditions (e.g., it appear to be noise), the signal processor then selects the next most dominant microphone signal. The signal processor may then, for example, continue selecting and decoding signals using this order of dominance until a microphone signal is decoded that meets specified conditions (e.g., the signal appears to include speech or music). It should be noted, however, that these are merely exemplary strategies that may be employed for selecting amongst multiple microphone signals, and in other embodiments other strategies may be used. 
         [0054]    Another exemplary combining strategy that may be employed is for the hearing device  200  to use a weighting system. For example, the signal processor  240  may instruct the selection circuit  219  to individually weight the different signals and then combine the weighted signals. This may be accomplished, for example, by the selection circuit applying fixed weights (e.g., weights specified by the recipient using the user interface or a strategy that weights signals from more forward facing sound elements higher) to each of the signals. Or, for example, the selection circuit  219  may examine each of the input signals and then weight the signals based on this analysis. One exemplary strategy for analyzing the signals is for the selection circuit  219  to examine each signal to determine if the signal appears to include speech information. If so, the selection circuit  219  may give a higher weight to the signal, while providing a lower weight to signals with little to no speech. Similarly, this strategy may also take into account the location of the sound input element  202 . For example, the hearing device  200  may be configured to more heavily weight signals from forward facing sound input elements  202  than from rear facing sound elements, even if both are determined to include speech information. This may be useful because in crowded rooms it is more likely that the recipient will be speaking with someone they are facing than someone behind them. 
         [0055]    In yet another exemplary combining strategy, the hearing device  200  may permit the recipient, via the user interface, to select a control setting that turns on a direction finding algorithm for selecting between microphones. Such algorithms are known to one of ordinary skill in the art. For example, simultaneous phase information from each receiver may be used to estimate the angle-of-arrival of the sound. Using such algorithms, the signal processor may determine a suitable microphone output signal or a plurality of suitable microphone outputs to use in providing the sound to the recipient. 
         [0056]    It should be noted that these are but some exemplary combination strategies that a bone conduction device may be able to use in combining signals from a plurality of sound input elements, and in other embodiments other strategies may be used. Additionally, although the embodiments are discussed with reference to the recipient selecting the combining strategy, it should be understood that any user (e.g., the recipient, a doctor, a family member, friend, etc.) may make these selections. Or, for example, a particular combining strategy may be fixed in hardware or software of the hearing device. Further, as discussed above, in embodiments, the recipient may be able to use a user interface  212  for the hearing device  200  to select and combination strategy to be used, such as the above referenced U.S. patent application by John Parker, Christian Peclat, and Christoph Kissling, entitled “A Bone Conduction Device with a User Interface.” 
         [0057]    As noted above in certain embodiments, the hearing device may select and use only signals from the forward facing sound input element(s). Or, for example, the hearing device may weight signals from forward facing sound input elements higher than rear facing sound input elements. Further, in certain embodiments the anchor system for the hearing device may implanted on either the right or left ear of a recipient. For example, a doctor may wish to implant the hearing device&#39;s anchor system on the side of the recipients head that the doctor believes will provide the recipient with the best hearing. Thus, doctors would like the flexibility to install anchor systems on either the left or right side of a recipients head. Accordingly, hearing devices in accordance with embodiments of the present invention may be configured so that the hearing device may be used both with anchor systems implanted on the right side and left side of a recipients head. However, because the hearing device may be implanted on either side of a recipients head, it may not be able to tell during manufacture of the hearing device which microphone(s) will be forward facing and which microphone(s) will not be forward facing. The following disclosure provides a description of an exemplary mechanism that a hearing device may employ to determine the forward facing microphone(s). 
         [0058]      FIG. 4  illustrates a close-up view of an exemplary mechanism that a hearing device may use to determine whether it is attached on the left or right side of a recipient. This exemplary mechanism may be used with a hearing device such as bone conduction device  300  illustrated in the above-discussed  FIG. 3 . This exemplary mechanism uses two different types of abutments  364 , one type for each side of the head. The different types of abutments (i.e., the left and right types) may be marked with words (e.g., “Right” and “Left”), use unique colors, or use some other mechanism to help a doctor quickly identify the type of abutment. Further, the different abutment types (i.e., left and right) may have a slightly different shape that may be detectable by the bone conduction device  300  so that the hearing device may determine to which side of the recipient the bone conduction device  300  has been attached. In the example of  FIG. 4 , the abutment  364  for one side includes an indentation in the center of its top face (i.e., the face of the abutment that faces the hearing device), while the abutment for the other side does not include such an indentation but instead has a flat surface along its top face. For explanatory purposes,  FIG. 4  will be discussed with reference to abutment  364  including an indentation, and this will be assumed in this example to be the left side abutment. In other embodiments, abutment  364  may have another type of recess, such as an opening, or aperture. As used herein the term “recess” refers to any type of indentation, hollow, slit, opening, or aperture. 
         [0059]    As illustrated in  FIG. 4 , the bone conduction device  300  includes a mechanical switch  412 . This switch  412  may be installed at any suitable location in the bone conduction device. For example, in an embodiment, switch  412  may be mounted on the inside or outside of second housing portion  325   b.  Further, switch  412  may be any suitable type of switch, such as, for example, an electronic switch, a mechanical switch, or a magnetic switch. For simplification, second housing portion  325   b  is not illustrated in  FIG. 4  As noted above, in this example, abutment  364  includes an indentation  406  located on the surface  408  of the abutment. This indentation  406  is sized to receives a protrusion  410  (e.g., a pin) from the bone conduction device  300 . Thus, if the protrusion  410  fits within the indentation  406 , bone conduction device  300  will know it is on the left side, while if there is no indentation then the protrusion will not be able to extend into the abutment  364  and the bone conduction device will know that it is located on the right side of the recipient. Protrusion  410  may be include in a spring loaded housing  413  that may be mounted, for example, on the inside or outside of second housing portion  325   b  or any other suitable location. If housing  413  is mounted on the inside of second housing portion  325   b,  the protrusion  410  may extend through opening  368  in the second housing portion  325   b  and into coupling device  360  so that protrusion  410  will fit in indentation  406  when the bone conduction device  300  is attached to abutment  364 . The protrusion housing may include a spring  414 , such that when there is no indentation in the abutment  364 , the protrusion is pushed back, while if there is an indentation  406 , the spring  414  pushes protrusion  410  into the indentation. 
         [0060]    Protrusion  410  may further include an arm member  415  that will contact switch  412  when protrusion  410  fits in indentation  406  but will not contact switch  412  when abutment  364  does not have an indentation and protrusion  410  (and accordingly its arm member  415 ) are thus pushed back towards the protrusion housing  413 . Thus, in this example, switch  412  determines that the bone conduction device  300  is attached to the left side if the switch  412  is contacted by the arm member  415 , and determines that the bone conduction device  300  is attached to right side if arm member  415  is not in contact with the switch  412 . Switch  412  may then send an indication to, for example, the signal processor of the bone conduction device  300  that indicates which side the bone conduction device  300  is attached. Or, for example, the switch  412  may simply send a signal indicating whether the arm member  415  is touching the switch (e.g., switch closed) or not (e.g., switch open). The signal processor may store information that specifies whether the bone conduction device  300  is connected to the left or right side of the recipient based on the possible signals from the switch  412 . For example, the signal processor may store information that specifies that the signal processor should consider the bone conduction device connected to the left side if it receives a switch closed signal from the switch  412 , and should consider the bone conduction device connected to the right side if the signal processor receives a switch open signal from the switch  412 . 
         [0061]    It should be noted that the embodiment of  FIG. 4  is but one exemplary embodiment and in other embodiments other suitable mechanisms may be used for determining to which said of a recipient a bone conduction device is attached. For example, in other embodiments the switch and protrusion may be located in a different location on bone conduction device  300 . Or, for example, bone conduction device  300  may instead use an electrical switch, such as a magnetic switch that indicates the presence of a particular magnetic field, and corresponding magnets may be placed in one type of abutment (e.g., for the left side of the recipient) and not included in the other type of abutment (e.g., for the right side). 
         [0062]      FIG. 5  illustrates the conversion of an input sound signal into a mechanical force for delivery to the recipient&#39;s skull in accordance with embodiments of bone conduction device  300 . At block  502 , bone conduction device  300  receives a sound signal. In certain embodiments, the sound signal is received via microphones  302   a  and  302   b.    
         [0063]    At block  504 , the signal is selected by the input selection circuit. The sound input selection circuit determines which signal or signals is to be output, based on the manual or automatic settings discussed above. 
         [0064]    At block  506 , the sound signal received by bone conduction device  300  is processed by the speech processor in electronics module  304 . As explained above, the speech processor may be similar to speech processors used in hearing aids. In such embodiments, speech processor may selectively amplify, filter and/or modify sound signal. For example, speech processor may be used to eliminate background or other unwanted noise signals received by bone conduction device  300 . In other embodiments, as discussed above, the speech processor may include programming to select a signal or combine signals, resulting in an improved percept by the recipient. 
         [0065]    At block  508 , the processed sound signal is provided to transducer  306  as an electrical signal. At block  510 , transducer  306  converts the electrical signal into a mechanical force configured to be delivered to the recipient&#39;s skull via anchor system  308  so as to illicit a hearing perception of the sound signal. 
         [0066]    Although the above description was discussed with reference to the recipient using the hearing device, it should be understood that this was provided for explanatory purposes and the hearing device and its user interface may be used in a similar manner by any user (e.g., doctor, family member, friend, or any other person). 
         [0067]    Although the present invention has been fully described in conjunction with several embodiments thereof with reference to the accompanying drawings, it is to be understood that various changes and modifications may be apparent to those skilled in the art. Such changes and modifications are to be understood as included within the scope of the present invention as defined by the appended claims, unless they depart there from.