Patent Publication Number: US-9407994-B2

Title: Direct drive micro hearing device

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of U.S. patent application Ser. No. 13/487,597 filed on Jun. 4, 2012, which claims priority to U.S. Provisional Application No. 61/492,646 filed Jun. 2, 2011, the entire disclosure of which are incorporated herein by reference. 
    
    
     FIELD 
     The present disclosure relates to a hearing device and, more particularly, to a device that can mechanically drive the ossicular chain while being located in the ear. 
     BACKGROUND 
     Conventional hearing aids rely on amplification of sound to improve hearing. This approach has several disadvantages. First, acoustic energy applied to the ear canal results in the occlusion effect, which occurs when bone-conducted sound energy trapped within the ear canal vibrates the cartilaginous portion, and results in unnatural sound quality due to an increased low frequency gain. This unnatural sound quality is especially bothersome to people with mild hearing loss. The occlusion effect increases with the volume of trapped air within the ear canal. Second, the output sound energy from the speaker may escape and re-enter the microphone, causing feedback when the amplification from microphone to speaker is greater than the attenuation from speaker to microphone. The problem of feedback is particularly problematic in patients with moderate or severe hearing loss where significant amplification is required, especially in the high-frequency region. It is also a problem for miniaturized devices where the microphone and acoustic driver are close together. 
     Some hearing aids attempt to solve the occlusion effect by adding a vent to the earmold to allow sounds trapped in the ear canal to escape. A larger vent diameter and shorter vent length would be more effective in reducing occlusion. However, a tradeoff of a larger vent diameter and short vent length is that such a vent provides less attenuation from a speaker to a microphone and thus, increases the likelihood of feedback. The problem feedback is overcome by increasing the separation between the microphone and speaker, usually by increasing the size of the hearing aid (in order of increasing size and visibility) from completely-in-the-canal to in-the-canal to in-the-ear to behind-the-ear. Patients, however, generally do not want to wear larger hearing aids due to their appearance and attached stigma. Although digital feedback management techniques can be applied, the state-of-the-art feedback management algorithms lead to signal degradation. 
     Micro hearing aids have been developed, but they suffer from the feedback problem just described. One of the newer hearing aids on the market (Lyric, InSound Medical Inc.) is small enough to be inserted deep into the bony part of the ear canal without being visible. The device eliminates the stigma attached to hearing aids and reduces the occlusion effect by reducing the amount of sound generated in the ear canal. However, due to feedback problems associated with a short distance between microphone and speaker, the micro hearing aids are typically only suitable for persons with mild hearing loss who do not require high amplification. 
     Alternatives to conventional hearing aids include the semi-implantable, implantable or fully implantable middle ear transducer. An early device (Direct System, Soundtec Inc.), now withdrawn from the market, consisted of a magnet attached to the ossicles (incudostapedial joint). The magnet was driven by an electromagnetic field produced by the external unit, consisting of a deeply fitted earmold housing an inductive coil, held approximately 2 mm lateral to the tympanic membrane, and a behind the ear (BTE) device housing the other electronic parts. The Vibrant Soundbridge (Med-El Corp.) consists of two parts attached by magnets—an implanted part consisting of the receiving coil, electronics and transducer, and an external part housing the microphone, speech processor, battery and transmitting coil. The Carina (Otologics LLC), which is available in Europe and currently under clinical trial in the US, is fully implantable. These devices translate sound energy into mechanical energy via a piezoelectric actuator that directly drives the ossicular chain. By having a mechanical rather than an acoustic output, the problem of acoustic feedback is eliminated. By driving the ossicles directly, the device may eliminate the occlusion effect and can provide a better sound quality compared to conventional hearing aids. However, major disadvantages of these devices that have reduced their acceptance include prohibitive cost, the need for an invasive surgery, the need for a second device with a microphone, and the requirement of an additional surgery for removal if there is a problem with the device. On the positive side, clinical studies showed that most patients preferred the sound quality of their middle ear implant over their hearing aid and thought that the feedback problem had been resolved. 
     The current state of art does not provide a satisfactory way to restore hearing without one or more of the follow disadvantages; feedback, occlusion effects, easily visible, stigma, invasive surgery, expensive and/or surgery for removal. Thus, there exists a desire for a device which overcomes one or more of the aforementioned drawbacks. 
     BRIEF SUMMARY OF THE EMBODIMENTS 
     The various embodiments provided herein are generally directed to systems and methods for a hearing device that is placed in the ear to drive a portion of an ear, such as the ossicular chain. In one embodiment, a hearing device includes a microphone configured to receive sound, an interactive tip and an actuator including an actuator element and preload force element, the preload force element configured place the interactive tip in contact with a portion of an ear. The hearing device also includes circuitry coupled to the microphone and actuator, the circuitry configured to process sound received by the microphone and drive the actuator based on processed sound. The actuator drives the interactive tip relative to a portion of an ear based on one or more signals received from the circuitry. 
     Another embodiment is directed to a two-part configuration for a hearing device for an ear including active and passive sections. The active section includes a microphone configured to receive sound and circuitry coupled to the microphone, a first actuator component, and circuitry configured to process sound received by the microphone and drive the first actuator component based on processed sound. The passive section, which is separate from the active section, includes an electromagnetic actuator and interactive tip. The electromagnetic actuator of the passive section is driven by the first actuator to drive a portion of the ear based on one or more signals received from the circuitry. 
     Other aspects, features, and techniques will be apparent to one skilled in the relevant art in view of the following detailed description of the embodiments 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other aspects, features, and techniques will be apparent to one skilled in the relevant art in view of the following detailed description of the embodiments 
         FIG. 1  depicts a sectional view of a typical ear; 
         FIG. 2  depicts placement of a wearable hearing device according to one embodiment; 
         FIG. 3  depicts a cross sectional view of a wearable hearing device according to one embodiment; 
         FIG. 4  depicts an isometric view of a hearing device according to one embodiment; 
         FIG. 5  depicts schematic diagram of an actuator and preload force arrangement according to one embodiment; 
         FIG. 6  depicts hearing device charging according to one embodiment; 
         FIG. 7  depicts a process for implementing an emergency stop mechanism according to one embodiment; 
         FIGS. 8A-8B  depict a system for installing a device using a multi-part system according to one embodiment; 
         FIG. 9  depicts a hearing aid device configured to interface with the tympanic membrane using fluid according to one embodiment; 
         FIGS. 10A-10B  depict an actuator according to one or more embodiments; 
         FIG. 11  depicts a simplified diagram of a hearing aid device configuration according to one or more embodiments; 
         FIG. 12  depicts a block diagram layout of a preload force and actuator in series according to one embodiment; 
         FIGS. 13A-13F  depict various methods to reduce or eliminate feedback according to one or more embodiments; 
         FIGS. 14A-14D  depict methods of positioning and attaching a device with external components according to one or more embodiments; 
         FIG. 15  depicts the use of an external fan to help keep the ear canal clean and dry according to one embodiment; 
         FIGS. 16A-16C  depict methods of attaching a device according to one or more embodiments; 
         FIGS. 17A-17B  depict hearing aid device associated with a two-part configuration according to one embodiment; 
         FIG. 18  depicts a schematic of a hearing device with an active suspension element according to one embodiment; 
         FIGS. 19A-19B  depict contact probe geometries to reduce the contact area on the tympanic membrane according to one embodiment; 
         FIG. 20  depicts a process for using fluid between the contact probe and tympanic membrane according to one embodiment; 
         FIGS. 21A-21D  depict utilizing an insert in the tympanic membrane for actuation according to one or more embodiments; and 
         FIG. 22  depicts the use of direct hearing device as a protective hearing apparatus according to one embodiment. 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     Overview and Terminology 
     One embodiment of the disclosure is directed to a wearable hearing device that is placed in the ear and configured to drive at least one portion of the ear. For example, in one embodiment, a hearing device includes a microphone configured to receive sound and an actuator. The actuator may be a voice coil actuator and can include an actuator element and preload force element. The preload force element can place an interactive tip of the hearing aid device in contact with the portion of the ear. The hearing device may additionally include circuitry coupled to the microphone and actuator, the circuitry configured to process sound received by the microphone and drive the actuator based on processed sound. Based on one or more signals received from the circuitry, the actuator can drive an interactive tip relative to a portion of an ear canal. 
     In a preferred embodiment, the hearing device is placed deep in the ear canal and drives the ossicular chain at the umbo using a voice coil actuator. This embodiment comprises a microphone, battery, circuitry, charging coil, voice coil actuator, preload spring, housing and interface tip. The preload spring can keep the interface tip in contact with the umbo and allows for a large range of acceptable device placement positions. The sound received by the microphone is processed by the circuitry, which in turn drives the voice coil actuator with the proper mechanical motion to mimic and amplify the sound received. 
     In one embodiment, a hearing aid device mechanically drives the ossicular chain. According to another embodiment, energy is transferred to the portion of the ear canal by at least one of electronic, electromagnetic, acoustic, photonic, vibration, magnetic, and mechanical means. In yet another embodiment, the portion of the ear receiving the actuation may relate to one of the umbo, tympanic membrane, ear canal and ossicles of a user for perception of the sound. 
     Further embodiments include additional features and teachings disclosed below and can be utilized separately or in conjunction with other features and teachings to provide a bone conduction device without the need for a protrusion through the skin. Representative embodiments can include many of these additional features and teachings both separately and in combination. 
     In some instances, the various features of the representative examples provided herein may be combined in ways that are not specifically and explicitly enumerated in order to provide additional useful embodiments of the present teachings. 
     As used herein, the terms “a” or “an” shall mean one or more than one. The term “plurality” shall mean two or more than two. The term “another” is defined as a second or more. The terms “including” and/or “having” are open ended (e.g., comprising). The term “or” as used herein is to be interpreted as inclusive or meaning any one or any combination. Therefore, “A, B or C” means “any of the following: A; B; C; A and B; A and C; B and C; A, B and C”. An exception to this definition will occur only when a combination of elements, functions, steps or acts are in some way inherently mutually exclusive. 
     Reference throughout this document to “one embodiment,” “certain embodiments,” “an embodiment,” or similar term means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of such phrases in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner on one or more embodiments without limitation. 
     Exemplary Embodiments 
     Referring now to the figures,  FIG. 1  depicts a sectional view of a typical ear including ear canal  100 , ossicles  102 , tympanic membrane  104  and cochlea  106 . As discussed herein, a herein device may be placed in ear canal  100  to drive one or more portions of an ear. 
       FIG. 2  depicts placement of a wearable hearing device  108  according one or more embodiments. Wearable hearing device  108  may be placed deep in the ear canal so that it cannot be seen. In some situations, it might be acceptable that wearable hearing device  108  is visible and therefore, can extend out of ear canal  100  and in particular out of opening  107  of ear canal  100 . In one embodiment, the middle ear is mechanically driven by wearable hearing device  108 . Hearing device  108  can be positioned/located near the tympanic membrane  104 . Wearable hearing device  108  is not required to be located near the tympanic membrane  104  if an extended mechanical connection is provided between the hearing device and the tympanic membrane. 
     Referring now to  FIG. 3 , a cross sectional view is depicted of a hearing aid device according to one or more embodiments. Hearing aid device  109  includes circuitry  110  which includes one or more elements for signal processing, recharging, programming and additional functions of the hearing aid device. Microphone  112  is located at the end of hearing aid  109  and faces the entrance of the ear canal, opening  107 , when worn. In certain embodiments, microphone  112  faces the tympanic membrane. Sound is received by microphone  112  and circuit  110  processes the received sound signal. A voice coil actuator is composed of magnet  130 , inner flux guide  128 , outer flux guide  126  and voice coil  122 . Circuit  110  drives current through voice coil  122  and a force is produced along, or at an angle to, the axis of hearing aid device  109  due to its interaction with the magnetic field in air gap  118 . In certain embodiments, this force will drive interface tip  120  which will be in contact with a portion of the ear, such as a portion of the ear canal, the tympanic membrane, or the umbo. The portion of the ear, such as the umbo, will displace from these forces and ultimately sound is perceived by the user. Preload spring  114  will hold interface tip  120  in contact with the umbo. Preload spring  114  and the voice coil actuator of hearing aid device  109  configuration is discussed in further detail below with respect to  FIG. 5 . In certain embodiments, the position of interface tip  120  does not influence force provided by the actuator. The hearing aid device of  FIG. 3  may be coated to prevent the device from corrosion and to maintain strength over time. Examples of such coatings include nickel, zinc, or epoxy. 
     Hearing aid device  109  includes housing  116 , the housing providing one or more features to hold the hearing aid device comfortably in place. Housing  116  can be designed in several ways. Hearing device  109  can include one or more elements to reduce sound from reaching one or more of portions of the ear canal, tympanic membrane, middle ear, or inner ear. In one embodiment, housing  116  may completely seal the ear canal and prevent natural sound from reaching the tympanic membrane. In another embodiment, housing  116  can be designed with baffles to impede sound from reaching the tympanic membrane while allowing the pressure to equalize between both sides of the device. Housing  116  may be designed have no sealing (nonoccluding) and allow free passage of sound. Housing  116  can also be designed to be flexible to allow relative movements between components to allow the device to better conform to the ear canal. 
     Battery  132  can power the device of  FIG. 3  and recharge coil  114  can recharge battery  132 . Recharging schemes are discussed in more detail below. In certain embodiments, recharging of hearing aid device  109  is not a requirement for successful implementation of the device. 
       FIG. 4  depicts an isometric view of a hearing aid device, such as the hearing aid device of  FIG. 3 , according to one or more embodiments. Circuit  110  is not sectioned in  FIG. 4  for added clarity on the configuration of the device. A configuration of outer housing  116  is also shown. Housing  116  includes one or more raised portions that can allow for placement of the hearing aid device in an ear canal and in some circumstances block one or more of moisture, fluid, aid and sound from penetrating a portion of the hearing aid including the interface tip when worn. 
       FIG. 5  depicts a schematic diagram illustrating an actuator and preload force arrangement according to one or more embodiments. A hearing aid, as discussed herein, can include an actuator, preload force arrangement and interface tip. Schematically, the preload force is displayed as spring  134 , the actuator is displayed as force element  136  and the interface tip is labeled  138 . When spring  134  is displaced, a force is generated to oppose the direction of motion. The opposing force can be independent of, proportional to, or a complex function of the displacement. Force element  136  allows free movement of interface tip  138  and at any position can provide an arbitrary mechanical output (e.g. force, displacement, velocity). This arrangement decouples the preload force from the actuator, making the properties of each independent of the other. The arrangement enables interface tip  138  to be displaced an arbitrary distance with no effect on the output of the actuator (e.g., force element  136 ). The arrangement also allows the preload force and actuation force to be very different in magnitude. For example, the preload force can provide 1 mg of force while the actuator provides 1 g of force. If the preload force and actuator were in a series arrangement, this would not be possible since the force of one must react the other. 
     In one embodiment, the preload force can be provided by a typical spring, in which case the force provided would be proportional to the displacement. The preload force can also be composed of several springs either in series and/or parallel and are configured to provide a tailored force based on a displacement profile. In certain embodiments, the preload force element need not be a separate element. For example, a voice coil according to one or more embodiments of a hearing aid device can provide a preload force using a DC bias and the actuation force would be superimposed onto the DC bias signal, essentially decoupling the two forces. In a similar fashion, a voice coil can provide a complex preload force profile while still providing an independent actuation force. 
     In certain embodiments, the voice coil actuator and preload force arrangement of  FIG. 5  may allow for a hearing aid device to provide a large range of acceptable distances for the hearing aid device to be placed in relation to the tympanic membrane with no influence of the actuation force. The preload force element comfortably holds the interface tip against the tympanic membrane while the actuator drives the tympanic membrane with an arbitrary force. Therefore, the actuator and preload force arrangement eases the requirements of the device placement position and can reduce the chances of tympanic membrane perforation. This arrangement also allows the tympanic membrane to deflect due to outside influences (e.g. pressure differences due to elevation change) without influencing the performance of the actuator. The performance and force generated are also not influenced by the device placement, which is desirable since placement of the device could move either intentionally or unintentionally. 
       FIG. 6  depicts a graphical representation of charging a hearing device. According to one embodiment, a hearing device, such as hearing aid device  109  can receive energy from a source placed near and/or in contact with the hearing device. Energy may be transferred by electronic, electromagnetic, acoustic, photonic, vibrational, magnetic, and/or mechanical means. In one embodiment, ear worn unit  140  is placed in an ear and energy  144  is transferred to hearing aid device  142 . Once charging is complete, ear worn unit  140  can be removed. Energy  144  can be electromagnetic energy that can be picked up by an inductive coil in device  142 . Energy  144  can be light and device  142  will have a solar cell to convert the light to energy. Energy  144  can be sound that oscillates a member on the device to generate electricity. Hearing aid device  142  can be configured to not transfer this sound to the user or it may be outside of the audible range. Energy  144  can be transferred to hearing aid device  142  via a wired connection, in which case hearing aid device  142  includes a mechanism for easily attaching and removing the wired connection. In one embodiment, ear worn unit  140  may include a mechanism that provides very little force against the device and therefore is unable to move the device position, but still establish a proper electrical connection. A magnetic connector can also be used to implement the method described above. 
       FIG. 7  depicts a graphical representation for implementing an emergency stop mechanism, such as a noncontact method for stopping hearing aid device  148 . When magnet  146  is placed in the ear, its magnetic field will pull an item, depicted as  150 , away from device  148 . Item  150  may include a fuse that when removed, prevents the hearing aid device from operating. Magnet  146  can be sized to prevent contact with hearing aid device  148  and to prevent potential damage to the tympanic membrane. Item  150  may also be located in the device. As such, item  150  can my fixed within device  148  to prevent item  150  getting stuck in the ear canal. Alternatively, a reed switch may also replace item  150 . In certain embodiments, the device would be designed to not turn on once the reed switch is trip. This will allow magnet  146  to be removed and keep device  148  in the off state. 
       FIGS. 8A-8B  depict a system for installing a hearing aid device using a multi-part system. According to one embodiment, insertion of a hearing aid device can be facilitated by using a multipart system including a sleeve for a hearing aid device. In  FIG. 8A , a cross sectional view of sleeve  152  can be easily inserted and placed in the ear canal. Sleeve  152  can be made with a large hole through the center, allowing for easy visual inspection. Sleeve  152  is designed to stop component  154  at the proper distance from the tympanic membrane as depicted in  FIG. 8B . This enables blind insertion of component  154 , such as a hearing aid device, without any risk of inserting it too far into the ear canal. In another embodiment, the interface tip of a hearing aid device can be part of the sleeve. In this case, it is possible to visually inspect the contact of the interface tip with the tympanic membrane/umbo since the sleeve can be made clear or have inspection ports added to it. The second component that is placed blind would consist of the other components of the hearing aid device (e.g. actuator, microphone, electronics). 
     A number of additional methods can be used to aid in the placement of a hearing aid device. In one embodiment, a hearing aid device can vibrate the interface tip during insertion so the user would hear when the device comes in contact with the tympanic membrane. For visual inspection, a hearing aid device may include one or more of providing a hearing aid device housing that is clear, providing a hole placed through the device, providing a groove placed on the outside of the device, having the device be made smaller than the ear canal diameter, and providing the external part to include a retractable feature. Special placement tools may be designed to assist in the visual inspection during placement using mirrors, cameras, etc. 
       FIG. 9  depicts a hearing aid device configured to interface with the tympanic membrane using fluid according to on embodiment. Fluid can be used for mechanically coupling a hearing aid device to the tympanic membrane as depicted in  FIG. 9 , in which hearing aid device  156  has an actuator that displaces fluid  158 . When pressure is produced in fluid  158  by the actuator of hearing aid device  156 , the pressure will displace the tympanic membrane and will be perceived as sound by the user. Hearing aid device  156  completely seals the ear canal and prevents fluid  158  from leaking around device  156 . 
     In an alternative embodiment, instead of free fluid between the device and tympanic membrane, a fluid filled pouch can be used that interfaces with the tympanic membrane. Using a fluid filled pouch can eliminate the need for the device to seal the ear canal and can be easier to install since the hearing aid device and fluid are individually contained. 
       FIGS. 10A-10B  depict an actuator according to one or more embodiments.  FIG. 10A  shows a cross-section of an isometric view of a hearing aid device.  FIG. 10B  depicts a cross-section of a side view of actuator  170 , wherein elements of  FIG. 10A  correspond to elements of  FIG. 10B . Actuator  170  is similar to the actuator described with reference to  FIG. 3 , however, suspension of voice coil  172  is on both ends. Permanent magnet  160  forms a flux circuit with inner rod  162 , flux guide  164  and flux guide  166 . An air gap, which may or may not include or be a fluid gap, exists between flux guide  166  and inner rod  162 . Portions of the flux guides are interrupted to allow suspension arms  174  and  176  to contact outer housing  171 . 
     The embodiment of  FIGS. 10A-10B  depict three suspension arms on either side of voice coil  172 , but any number and combination of suspension arms can be used. Suspension arms  174  and  176  are integrated into sleeve  168  to ease construction of the device, in some instances integration of suspension arms  174  and  176  is not required. 
     According to another embodiment, a hearing aid device and/or actuator need not be circular, but may be in the form of an ellipse, rectangle or other shape. Similarly, components of a hearing aid device do not need to be monolithic. For example, a ring magnet is shown in the embodiments above but this magnet can be replaced by two or more other magnets to help form a desired shape. 
       FIG. 11  depicts a simplified diagram of a hearing aid device configuration according to one or more embodiments. Hearing aid device  177  includes microphone  178  connected to circuitry  180 . Circuitry  180  can contain a power source, drive electronics, control electronics, signal processing, charging elements and/or charging circuitry. Components  184  and  186  of hearing aide device  177  form electromagnetic actuator  190 , and component  182  provides a spring element between components  184  and  186 . 
     Component  182  can be a spring or flexure element, such that the configuration of  FIG. 11  allows actuator  190  to displace and provide a preload force against the object it is driving. In one embodiment, contact point  188  is connected to actuator  190  and interfaces with the ossicles. Sound received by microphone  178  is transmitted to circuitry  180 . Circuitry  180  can perform signal processing operations on the microphone signal, (e.g. amplification, filtering). The processed signal from circuitry  180  is used to drive actuator  190  which ultimately drives the ossicles of the user and sound is perceived. In this way, hearing aid device  177  converts acoustic energy into mechanical energy that can be perceived as sound. 
     The housing of hearing aid device  177  can be designed to occlude the ear canal and block natural sounds from reaching the tympanic membrane, and thus, can also be used as a communication device in noisy environments. In this case, a hearing aid device would not drive the tympanic membrane based on the sound entering the ear (e.g. a typical hearing aid), but instead would drive the tympanic membrane based on a signal transmitted to the hearing aid device by another device (e.g. cell phone, mp3 player). This signal can be transmitted by wired or wireless means to the hearing aid device. Since the hearing aid device directly drives the tympanic membrane, there are no occlusion effects even though the entire ear canal is blocked. In this application, it may not be necessary to have the hearing aid device completely hidden in ear canal and, in fact, a visible device offers several advantages. First, it would be easy to determine if the user was wearing ear protection. Second, the user would have easy access to controls for adjusting settings of the device such as adjusting the volume and switching between different communication channels. Third, the user can remove the device without the aid of special equipment or assistance of another person. 
       FIG. 12  depicts a block diagram layout of a preload force and actuator in series which may be employed by a hearing aid device according to one or more embodiments. Schematically, the preload force is displayed as spring  192 , the actuator is displayed as force element  194  and the interface tip is labeled  196 . When preload force element  192  is displaced, a force is generated to oppose the direction of motion. The opposing force can be independent of, proportional to, or a complex function of the displacement. Force applied by force element  194  will be transmitted to interface tip  196  and will be reacted by preload force element  192 . Unlike the layout shown in  FIG. 5 , the preload force and actuator force in  FIG. 12  are dependant on each other since one must react the other. The preload force applied by preload force element  192  will still be able to hold interface tip  196  against the tympanic membrane with the force going through force actuator  194 . This configuration enables actuators that have no floating travel to drive the tympanic membrane. Non-floating actuators include, but are not limited to, piezoelectric actuators, balanced armatures, solenoids, pneumatic actuators, and electromagnetic actuators. The effects on performance from preload force element  192  reacting the force of actuator  194  are reduced if the preload force needed to comfortably hold interface tip  196  against the tympanic membrane is much larger than the force needed to drive the tympanic membrane to produce sound. Even if the preload force is smaller than the actuation force, movement can still be transferred to the tympanic membrane. Configuration of such a device would be similar to the basic device configuration shown in  FIG. 11 , but instead of actuator  190  being composed of two parts, one attached to the housing ( 184 ) and the other attached to the moving element ( 186 ), the actuator would only be attached to the moving element. This change in actuator location results in the preload force and actuator being arranged in series and enables non-floating actuators to be utilized for driving the tympanic membrane. 
       FIGS. 13A-13F  depict graphical representations of a hearing aid device configured to reduce or eliminate feedback according to one or more embodiments.  FIG. 13A  is a schematic diagram of hearing aid device  204  in ear canal  202 . Interface probe  206  enables hearing aid device  204  to actuate tympanic membrane  208 . Microphone  226  is used to record sound entering the ear. Attachment of the hearing aid device  204  to ear canal wall  200  is not shown.  FIG. 13B  depicts sound  210  traveling towards tympanic membrane  208 . Actuation, as shown by  214 , of tympanic membrane  208  could produce sound  212  that would travel away from tympanic membrane  208 . If sound  212  has sufficient intensity to be picked up by microphone  226 , it could produce feedback within the direct hearing system. To reduce this feedback, several methods can be employed. In one embodiment, a directional microphone can be positioned to be most sensitive to sound traveling towards tympanic membrane  208 . This method would reduce the sensitivity of direct hearing microphone to sounds traveling away from the tympanic membrane and therefore reduce the amount of feedback in the direct hearing system. Another method of reducing feedback would be the use of baffling around device  204  to reduce the intensity of sound  212 . Sound  210  would reach microphone  226  before reaching the baffling, whereas sound  212  would travel past the baffling, reducing its intensity, before reaching microphone  226 . 
     Another method, shown in  FIG. 13C  and  FIG. 13D , is to actuate tympanic membrane  208 , depicted as  220 , in response to sound  218  at the same time sound  218  contacts tympanic membrane  208 . In this method, positive (and negative) pressures of sound  218  will coincided with negative (and positive) pressures produced by actuation  220  and effectively cancel each other out, much like a noise cancellation system. This method also increases the efficiency of actuation  220  since sound  208  will aid in the movement of tympanic membrane  208 . 
     Another method includes using a sound inhibiting element to reduce the sound generated by the actuation of tympanic membrane  208 . As shown in  FIG. 13E , component  216  on interface probe  206  is a sound inhibiting element. Component  216  is designed in such a way that it would behave as a “bad speaker” and reduce the amount of sound generated during the movement of tympanic membrane  208 . Another embodiment of this method, not shown, is to have the sound inhibiting component attached to the surface of tympanic membrane  208 . This component would have similar sound inhibiting properties as element  216 . 
       FIG. 13F  displays a method of using microphones  222  and  224  to help reduce feedback. One method using this microphone configuration is to use the timing information between the sound received at microphone  222  and microphone  224 . This timing information will help determine the direction of sound travel of a particular waveform and can be used in a filter algorithm to attenuate the sound traveling away from tympanic membrane  208 . Another method using the microphone configuration is to have a directional microphone at position  222  that faces away from the tympanic membrane and a directional microphone at position  224  that faces towards the tympanic membrane. This method will also enable a filter algorithm to determine the direction a particular sound wave is traveling and can be used to attenuate the sound traveling away from tympanic membrane  208 . 
     If sound  212  is not a component of sound  210 , a filter can be used to reduce the feedback by reducing any frequency components not within the operating range of the device or the sound entering the ear. 
       FIGS. 14A-14D  depict methods of positioning and attaching a hearing aid device with external components. As shown in  FIG. 14A , hearing aid device  232  can be positioned and held in place by location component  230 . Location component  230  is separate from device  232  and would remain with the user on removal of device  232 . Location component  230  could be fixed in numerous ways including to the skin of ear canal  234 , under the skin, or cemented to the bone. Location component  230  and attachment points on device  232  could be made from ferromagnetic and/or magnets. As such, device  232  would be held in place by magnetic forces between itself and location component  230  and therefore would not need to penetrate through the skin. Location component  230  would aid in the placement of hearing aid device  232  by providing a repeatable and reliable method of attachment. This would reduce the precision needed when placing device  232  and enable more frequent removals. 
       FIG. 14B  shows location component  236  as a complete ring that would encompass ear canal  234 .  FIG. 14C  shows location component  238  as a partial ring that would be placed on one side of ear canal  234 .  FIG. 14D  shows location component  240  as multiple components that would be placed around ear canal  234 . In this case, three components are shown for location component  240 , but there could be any number of location components. 
       FIG. 15  depicts the use of an external fan to help keep the ear canal clean and dry. As shown in  FIG. 15 , air  250  from device  252  is directed into the ear canal by fan  254 . Device  252  could be a wearable device or handheld device. Device  252  could also be integrated into hearing aid device  251 . Device  252  would have an opening to allow air  250  to escape past it to aid in the air flow through the ear canal. Device  252  could also have a recharging unit, such as the one displayed by  FIG. 6 , integrated into the device to enable device  252  to both dry the ear canal and charge hearing aid device  251 . 
       FIGS. 16A-16C  depict methods of attaching a hearing aid device to allow free movement of particles, fluids, etc. around the device. As shown in  FIG. 16A , hearing aid device  262  could be attached to the walls of the ear canal by attachment component  260 . In a typical hearing device, attachment component  260  occludes the ear canal to reduce the potential for feedback. In this case, moisture and ear wax are trapped between the hearing aid device  262  and the tympanic membrane. Occluding the ear canal could lead to corrosion of the device, increased risk of infection and increased occlusion. To prevent these undesirable side effects, attachment component  260  could have openings around it and have limited contact with the ear canal. These openings can reduce the buildup of earwax by letting wax and/or other particles pass by hearing aid device  262 , allowing free movement of air to reduce moisture and risk of infection, and reducing the occlusion effect since the ear canal will not be occluded.  FIG. 16B  and  FIG. 16C  are sectional views of  FIG. 16A  as shown by section line a-a. In  FIG. 16B , attachment component  260  is composed of three components, one of which is labeled  264 . The attachment components could be realized by one or more attachment components. Also, component  264  could be a single component with multiple attachment arms protruding from it. Since there is limited contact with the ear canal, the advantages of a non-occluding attachment can be realized by this configuration. In  FIG. 16C , attachment component  260  is composed of component  266 , which has numerous holes around its perimeter. These holes would offer a non-occluding attachment point. 
     According to one embodiment, winged attachment component  264  depicted in  FIG. 16B  can collapse during insertion and extend when placed properly in the ear canal to hold the hearing aid device securely in place. Alternatively, the winged attachment component could be held in the collapsed position with a sleeve that is removed after insertion or release by other mechanical, chemical or electrical means. 
     In another embodiment, a hearing aid device may include a moldable polymer housing to facilitate secure fitting within the ear canal. The polymer will be flexible in the patient&#39;s ear to assure comfort during all types of movement. The polymer housing may be cured through ultra violet light, and thus, customized for each patient after device placement within the ear canal. According to an embodiment, the application of UV curable polymers to a hearing aid device also extends to the contact tip placement and shape. A curable polymer may be placed around the interface tip, thus providing a secure contact and secure placement on the tympanic membrane. If the application calls for breathability of the housing where the ear canal should not be completely occluded, the use of a porous polymer may be integrated to eliminate moisture buildup and corrosion. This porous polymer may be self assembling, or created through the use of a biodegradable mesh. Application of the polymer may include placing a mesh for a hearing device, and injecting a polymer mold to follow. After a chosen time period, the mesh will dissolve leaving a customized, breathable polymer housing. The housing may be waterproof to allow for swimming, showering, etc. without causing damage to the device. 
       FIGS. 17A-17B  depict a two-part embodiment of a hearing aid device.  FIG. 17A  shows a schematic of a two-part hearing aid device. Component  274  forms one part of the embodiment and components  286  forms the other part. In part  286 , attachment  270  attaches to the wall of the ear canal and provides compliance between the ear canal and magnet  276 . Passive magnet  276  can be driven by active component  274  to displace the tympanic membrane through interface  272 . Active component  274  would have an electromagnet that could control magnet  276  without making contact with part  286 . Since component  286  is passive and does not require a local power source, it can be made small, light and have a more permanent attachment to the user. This construction allows a skilled professional to locate and attach passive part  286 , since part  286  does not need to be removed to change batteries. Part  274  could then be removed and replaced with greater ease since it is not as tolerant to position and would not make contact with the tympanic membrane. 
       FIG. 17B  shows a simplified diagram of a two-part device configuration. The active part is formed by microphone  178 , circuitry  180  and component  280 . The passive part is formed by component  282 , component  284  and interface probe  188 . Microphone  178  is connected to circuitry  180 . Circuitry  180  can contain a power source, drive electronics, control electronics, signal processing, charging elements and/or charging circuitry. Components  280  and  282  form electromagnetic actuator  278  even though they are located on different parts of the device. Part  280  can move relative to part  282  without affecting the force in interface probe  188 , and therefore, the active part can be removed without disturbing the passive part of the device. Component  284  provides an element between component  282  and the ear canal which can be a spring or flexure element. This configuration allows component  282  to displace and provide a preload force against the object it is driving. Interface probe  188  is connected to component  282  and interfaces with the ossicles. Sound received by microphone  178  is transmitted to circuitry  180 . Circuitry  180  can perform signal processing operations on the microphone signal, (e.g. amplification, filtering). The processed signal from circuitry  180  is used to drive actuator  190  which ultimately drives the ossicles of the user and sound is perceived. In this way, the device converts acoustic energy into mechanical energy that can be perceived as sound in a two-part configuration. 
       FIG. 18  depicts a schematic of a hearing device with an active suspension element according to one or more embodiments. The device of  FIG. 18  may be an alternative arrangement for achieving a similar interface tip as discussed above with reference to  FIG. 5 . Actuators  290  and  292 , and an interface tip  294  allows for an actuator with no floating travel to decouple its internal stiffness from the contact pressure. Non-floating actuators include, but are not limited to, piezoelectric actuators, balanced armatures, solenoids, hydraulic actuators, pneumatic actuators, and electromagnetic actuators. In one embodiment, actuators  290  and  292  are non-floating actuators. Actuator  290  would have a relatively low internal stiffness and could arbitrarily adjust the force on interface tip  294 . This enables actuator  290  to behave as an active spring element that can adjust the force in interface tip  294  based on any number of parameters including contact pressure, displacement, tip velocity, etc. During the actuation of actuator  292 , actuator  290  could provide a reaction force that reduces coupling between the contact pressure and actuation force. This allows actuator  292  to have a large internal stiffness, such as a piezoelectric actuator, but still have large displacements and low contact pressures during device placement. This configuration is not limited to non-floating actuators and could include floating actuators in place of one or more of the non-floating actuators discussed above. 
       FIGS. 19A-19B  depict contact probe geometries to reduce the contact area on the tympanic membrane.  FIGS. 19A-19B  display two types of interface probe geometries. Reduced contact area is desirable to allow the tympanic membrane to breath and reduce the chance of infection and irritation. In  FIG. 19A , shaft  300  attaches to contact shape  302 . Not shown is the hearing device that drives shaft  300 . Contact shape  302  has numerous holes, one of which is labeled  304 . This construction enables the contact shape to contact a large portion of the tympanic membrane while minimizing the area that is covered by the contact geometry. In  FIG. 19B , shaft  306  attaches to a contact shape with multiple contact points, one of which is labeled  308 . Not shown is the hearing device that drives shaft  306 . This construction enables contact shape  302  to contact the tympanic membrane at multiple locations while minimizing the area covered by the contact tips. This construction distributes the load on the tympanic membrane while keeping the contact area to a minimum. The contact tip that is coupled to the umbo can be customized for each user for optimal function and fit. 
     According to another embodiment, a slippery, nonstick material could be used to construct or coat the contact area of the interface probe. The material/coating would allow water, debris, earwax, etc. to be carried away by the natural movement of the skin on the tympanic membrane. This would also reduce the moments that would be generated on the interface probe while contacting the tympanic membrane. 
     Another method to keep the tympanic membrane clean is to retract the interface probe during non-use and/or sleep periods. This method will enable the tympanic membrane to dry and reduce the amount of build up on the tympanic membrane. Retraction of the interface probe could be initiated by the user, based on one or more of the time of day, level of activity or on some other parameter. The retraction could be for long periods of time, such as during sleep, or could be at much shorter intervals, such as being in a quiet environment. During the retracted period, the interface probe could reengage with the tympanic membrane if a sound level above a specified threshold is measured. A power switch may be incorporated to improve upon battery life and extend the time between necessary charging periods. This power switch may correspond directly with the retraction of the interface probe allowing for the natural movement of the skin on the tympanic membrane to remove debris. 
       FIG. 20  depicts a process for using fluid between a contact probe and tympanic membrane. A simplified diagram is shown of contact between interface probe  310  and tympanic membrane  312 . Fluid  314  is placed between contact probe  310  and tympanic membrane  312  to eliminate contact of tympanic membrane  312  with solid material. Since fluid  314  is the contact material, one or more of water, debris, earwax, etc. can be carried away by the natural movement of the skin of the tympanic membrane. Fluid  314  could be replenished by an external supply through transfer component  316 . The external supply could be in the form of a reservoir on the hearing device that is supplied by the user or a doctor by a reservoir outside of the ear canal. Fluid  314  could be selected to reduce evaporation, such as oil, and/or could be a fluid that reduces the amount absorbed by the tympanic membrane. Transfer component  316  could be a tube that requires pressure to replenish fluid  314  or could be a wick, capillary or other component that able to replenish fluid  314  passively. In addition to fluid, this material that interfaces between contact probe and the tympanic membrane may be constructed of a soft flexible polymer. This material will still provide a delicate interface, while remaining robust for long term use. 
       FIGS. 21A-21B  depict one or more embodiments of utilizing an insert in the tympanic membrane for actuation. In  FIG. 21A , device  322  is located in an ear canal and is attached via attachment  320 . Insert  326  is fixed to the tympanic membrane. In one embodiment, a small incision is made into the tympanic membrane using a knife, needle, or other sharp device to fix insert  326 . Insert  326  could be a small device shaped like a pressure equalization tube and may be placed into the tympanic membrane. The insert can be placed such that flanges on the inside and outside of the tympanic membrane hold insert  326  onto the tympanic membrane. In another embodiment of the device, the device can be anchored to the malleus or include a portion that sits against the malleus. Unlike traditional tubes inserted in the tympanic membrane, insert  326  can be a magnet, ferrous, paramagnetic or any other material that reacts to magnetic fields. Insert  326  is not required to be tubular and could be completely solid. 
     According to another embodiment, device  322  can transmit magnetic fields  324  that can influence and actuate insert  326 . As such, device  322  can actuate the tympanic membrane without being in direct contact with the tympanic membrane. In the case that insert  326  is a magnet, device  322  can apply opposing forces on insert  326 . Other methods for attaching insert  326  include use of one or more of adhesives, sutures, surface tension, or by any other means. 
     In  FIG. 21B , device  332  has arm  336  with tip  338 . Insert  334  is similar to insert  326  in  FIG. 41A . Device  332  is capable of moving tip  338 . Tip  338  could be a permanent magnet or an electromagnet. Tip  338  is able to transmit a magnetic field and therefore the mechanical movement of tip  338  will actuate insert  334 . In the case that tip  338  is an electromagnet, the mechanical movement and electrically changing the magnetic field can produce intricate movements of insert  334 . 
     In  FIG. 21C , device  340  has arm  346  with tip  342 . Insert  344  is similar to insert  326  in  FIG. 21A . Device  340  is capable of moving tip  342 . Tip  342  mechanically attaches to insert  344  and enables device  340  to apply opposing forces on insert  344  and therefore the tympanic membrane. Tip  342  could be a permanent magnet or an electromagnet. 
       FIG. 21D  illustrates an alternative configuration for an insert in the tympanic membrane. The insert is composed of attachment  328  and actuation material  330 . Actuation material  330  reacts magnetic fields and can be of similar composition as insert  326  in  FIG. 21A . The configuration of  FIG. 21D  enables actuation material  330  to be located at a different location than the attachment point to the tympanic membrane. The forces applied to the tympanic membrane via actuation material  330  will be different based on the location of the attachment point and actuation material  330 . As such, forces that will be applied to the tympanic membrane may be customized. 
       FIG. 22  depicts the use of direct hearing device  348  as a protective hearing apparatus. Typical protective hearing devices passively or actively hinder sound entering through the ear canal, such as air conduction  350 , but sound transmitted through the bones such as bone conduction  352 , can still be heard and cause damage. Bone conduction hearing is caused by sound pressure waves that vibrate the skull and consequently the ossicular chain and fluid filled cochlea. However, since direct hearing device  348  will control the movements of the ossicular chain at the tympanic membrane, both mechanisms of sound transmission, that is bone conduction  352  and air conduction  350 , can be modulated and reduced. To achieve this type of hearing protection, direct hearing device  348  would monitor the movement of the ear drum and actively prevent the ear drum from moving. A more sophisticated method of this hearing protection would involve filters and additional sound processing, to allow only wanted sounds to be transmitted and block unwanted sounds. For example, filters could filter out certain damaging sounds while still facilitating hearing of close conversational sounds. Sounds can also be transmitted by radio, either wired or wirelessly while still maintaining noise cancelling abilities through filtering and occlusion of the ear canal. In this case, the tympanic membrane is driven by an external signal as opposed to environmental sound entering through the ear canal. This will allow the user to hear the signal transferred over the radio, while outside environmental sounds will be cancelled. All parameters can be customized for specific applications. 
     While this disclosure has been particularly shown and described with references to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the disclosure encompassed by the appended claims.