Patent Publication Number: US-2023156409-A1

Title: Compact hearing aids

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. Nonprovisional application Ser. No. 17/564,665, filed Dec. 29, 2021, which is a continuation of U.S. Nonprovisional application Ser. No. 17/089,155, filed Nov. 4, 2020, which is a continuation-in-part of U.S. Nonprovisional application Ser. No. 16/593,039, filed Oct. 4, 2019, and U.S. Nonprovisional application Ser. No. 16/593,070, filed Oct. 4, 2019, which both claim benefit of U.S. Provisional Patent Application Ser. No. 62/742,525, filed on Oct. 8, 2018, all of which are herein incorporated by reference in their entirety. 
    
    
     BACKGROUND 
     Field 
     Embodiments of the present disclosure generally relate to assistive hearing devices and methods of implantation thereof. More particularly, embodiments of the present disclosure are related to compact hearing aids mounted internally into an ear canal, for example, into or across the tympanic membrane, which provide vibration transduction to modulate the velocity or the position of the tympanic membrane. 
     Description of the Related Art 
     Hearing aids are well known and typically include a microphone, an amplifier, and a speaker. Typically, the microphone receives a sound wave and converts the wave into an electrical signal, the amplifier amplifies the electrical signal, and the speaker converts the amplified signal into amplified sound waves that impart vibrations to the tympanic membrane or ear drum in the ear. Traditionally, hearing aids are mounted outside the ear canal, particularly around the outer ear. The externally mounted hearing aid has the advantage of accessibility to change batteries and to adjust the volume of sound. However, many users find such externally mounted hearing aids to be relatively bulky and objectionable for cosmetic and comfort reasons. 
     An alternative to externally mounted hearing aids are internally mounted hearing aids disposed in an ear canal of a user. Conventional internally mounted hearing aids offer better cosmetic appearance, but have disadvantages as well. For instance, the typical internally mounted hearing aid blocks the majority, if not all, of the ear canal diameter. Such blockage can cause the body of the user to produce an excessive amount of ear wax in the ear canal and can cause ear infections. Further, the blocking of the ear canal obstructs the natural transmission of sound waves through the ear canal and negatively impacts the hearing quality. Unless a user is totally hearing impaired, any ability of the tympanic membrane to register the natural occurring sound waves is reduced or eliminated. Thus, the user is substantially dependent upon the sound fidelity of the hearing aid. Still further, the typical internally mounted hearing aids may still be somewhat visible in the ear canal. 
     Some hearing systems deliver audio information to the ear through electromagnetic transducers. A microphone and amplifier transmit an electronic signal to a transducer that converts the electronic signal into vibrations. The vibrations vibrate the tympanic membrane or parts of the middle ear that transmit the sound impulses without reconverting to audio sound waves. Historically, a separate magnet, or any suitable actuator, was remotely mounted at or near the tympanic membrane. The interaction between the magnetic fields of the transducer receiving the electronic signal and the magnet mounted at or near the tympanic membrane causes the magnet to vibrate and thus mechanically transmits the sound through the vibration to the ear at the cochlea. Typically, however, the remainder of the hearing aid is inserted into the ear canal or on the outer ear and can cause the problems discussed above. Still further, the transducers and/or magnets of the hearing aids are mounted in a relatively invasive procedure. For instance, one contact transducer having a magnet is installed by drilling through the mastoid bone, cutting through the tympanic membrane, microscopically drilling a bone structure, and screwing the magnet to any one or more of the middle ear bones. Such procedures are often painful and expensive, and can have serious complications. 
     As described above, there are various types of hearing aids that are used to amplify and transmit sound waves to the hearing center of the brain resulting in the perception of sound. However, conventional hearing aids do not selectively suppress sound waves generated by background noise and excessively loud noises while simultaneously transmitting normal speech and other desirable acoustic signals. Noise suppression could be used by astronauts on long duration missions such as the International Space Station or a Mars mission that want to selectively suppress background noise created by rotating machinery, air handling systems, and environmental control systems while still allowing the astronaut to hear the sound waves generated by other astronauts and other desirable acoustic signals. Amplification of selective frequencies could be used in a military operation, wherein sound waves generated by enemy combatants could be amplified and sent to the hearing center of the brain while all other sound waves are transmitted in a normal manner. Additionally, the traditional types of hearing aids do not allow a user to receive signals or sound waves that are not audible to a normal person, such as in covert communication. 
     Therefore, there is a need in the art for improved hearing aids, which can be inserted in the ear canal and/or through the tympanic membrane using minimally-invasive surgical procedures. 
     SUMMARY 
     The present disclosure relates to compact hearing aids, components thereof, and support systems therefor, as well as methods of insertion and removal thereof. The compact hearing aids generally include a sensor, such as a microphone, an actuation mass, an energy source for providing power to the compact hearing aid, a processor, and an actuator enclosed in a housing that is designed to be inserted through the tympanic membrane during a minimally-invasive outpatient procedure. In operation, the microphone receives sound waves and converts the sound waves into electrical signals. A processor then modifies the electrical signals and provides the electrical signals to the actuator. The actuator converts the electrical signals into mechanical motion, which actuates the actuation mass to create inertia internal to the housing, and the housing is configured to modulate the velocity or the position of the tympanic membrane. 
     In one embodiment, a tympanic membrane actuation assembly is disclosed. The tympanic membrane actuation assembly includes at least one mass configured to be disposed on at least one of a medial side or a lateral side of a tympanic membrane of a user, and at least one actuator coupled to the mass and configured to be disposed on at least one of a medial side or a lateral side of the tympanic membrane or through the tympanic membrane of a user, the actuator being configured to convert electrical signals into mechanical motion to move the mass and modulate the tympanic membrane. 
     In another embodiment, a hearing aid, which is insertable through a user&#39;s tympanic membrane to amplify certain frequencies and cancel other frequencies, is disclosed. The hearing aid includes a tympanic membrane actuation assembly, which includes at least one mass configured to be disposed on at least one of a medial side or a lateral side of the tympanic membrane of a user, and at least one actuator coupled to the mass and configured to be disposed on at least one of a medial side or a lateral side of the tympanic membrane or through the tympanic membrane of a user, the actuator being configured to convert electrical signals into mechanical motion to move the mass and modulate the user&#39;s tympanic membrane. 
     In yet another embodiment, a hearing aid, which is insertable through a user&#39;s tympanic membrane to amplify certain frequencies and cancel other frequencies, is disclosed. The hearing aid includes a housing having a first flange and a second flange having a groove therebetween, the housing encloses a microphone, a processor coupled to the microphone, and a tympanic membrane actuation assembly, which includes a mass, the mass having a first battery disposed in the first flange, and a second battery disposed in the second flange, the first battery being configured for placement on a lateral side of the tympanic membrane, the second battery being configured for placement on a medial side of the tympanic membrane, a connecting member coupling the first battery to the second battery, the connecting member being configured for placement through the tympanic membrane, and an actuator coupled to the mass and disposed within the connecting member, the actuator being configured to convert electrical signals into mechanical motion to move the mass and modulate the user&#39;s tympanic membrane. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only exemplary embodiments and are therefore not to be considered limiting of its scope. The disclosure may admit to other equally effective embodiments. 
         FIG.  1    is a cross-sectional schematic view of the anatomy of an ear having a hearing aid inserted through the tympanic membrane thereof. 
         FIG.  2    is a schematic plan view of a right tympanic membrane. 
         FIG.  3    is schematic perspective view of a compact hearing aid. 
         FIG.  4    is a cross-sectional view of the compact hearing aid of  FIG.  3   . 
         FIG.  5    is a plan view of an actuator. 
         FIG.  6    is a plan view of an alternative embodiment of an actuator. 
         FIG.  7    is a schematic perspective view of an alternative embodiment of a compact hearing aid. 
         FIG.  8    is a schematic perspective view of an alternative embodiment of a compact hearing aid. 
         FIGS.  9 A- 9 C  depict an alternative embodiment of a compact hearing aid. 
         FIG.  10    is a process flow of a method for inserting a compact hearing aid. 
         FIGS.  11 A- 11 B  depict the compact hearing aid of  FIGS.  9 A- 9 C  with a portion of an implantation tool at various stages of implantation. 
         FIG.  12    is a block diagram of an ASIC processor. 
         FIG.  13    is a cross-sectional view of a compact hearing aid having an alternative embodiment of an actuator. 
         FIG.  14    is a cross-sectional view of a compact hearing aid having an alternative embodiment of an actuator. 
         FIGS.  15 A- 15 B  depict an alternative embodiment of an implantation tool. 
         FIGS.  16 A- 16 C  depict an alternative embodiment of a compact hearing aid. 
         FIG.  17    depicts a schematic cross-sectional view of an actuation assembly of a compact hearing aid. 
         FIG.  18    depicts a schematic cross-sectional view of a compact hearing aid. 
         FIG.  19    depicts a schematic cross-sectional view of an actuation assembly of a compact hearing aid. 
         FIG.  20    depicts a schematic cross-sectional view of an actuation assembly of a compact hearing aid. 
         FIG.  21    depicts a top-down cross-sectional view of a portion of an actuation assembly of a compact hearing aid. 
         FIG.  22    depicts a top-down cross-sectional view of a portion of an actuation assembly of a compact hearing aid. 
         FIGS.  23 A- 23 D  depict an alternative embodiment of a compact hearing aid. 
         FIGS.  24 A- 24 F  depict an alternative embodiment of a compact hearing aid. 
         FIG.  25    depicts a cross-sectional view of an alternative embodiment of a compact hearing aid. 
     
    
    
     To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation. 
     DETAILED DESCRIPTION 
     The present disclosure relates to compact hearing aids, components thereof, and support systems therefor, as well as methods of insertion and removal thereof. The compact hearing aids generally include a sensor, such as a microphone, an actuation mass, an energy source for providing power to the compact hearing aid, a processor, and an actuator enclosed in a housing that is designed to be inserted through the tympanic membrane during a minimally-invasive outpatient procedure. In operation, the microphone receives sound waves and converts the sound waves into electrical signals. A processor then modifies the electrical signals and provides the electrical signals to the actuator. The actuator converts the electrical signals into mechanical motion, which actuates the actuation mass to modulate the velocity or the position of the tympanic membrane. 
     The Anatomy of the Ear 
       FIG.  1    is a cross-sectional schematic view of the anatomy of an ear  100  having a hearing aid inserted through the tympanic membrane thereof. The ear includes an outer ear  110 , an ear canal  112  coupled to the outer ear  110 , a tympanic membrane  114  disposed near a proximal end of the ear canal  112  from the outer ear  110 . The structure of the outer ear  110  provides a “funnel” to direct and amplify the amplitude of the sound waves into the ear canal  112 . An ossicular chain  115 , located in a middle ear and disposed on a medial side of the tympanic membrane  114  from the outer ear  110 , couples and amplifies vibrations from the tympanic membrane  114  to an inner ear having a spiral structure known as the cochlea  120 . The cochlea  120  converts the vibrations into impulses to the brain. 
     Hearing aids, such as hearing aid  122 , of the present disclosure can be inserted through the outer ear  110  into the ear canal  112  and at least partially through the tympanic membrane  114 . The hearing aid  122  generally includes a sensor, such as a microphone, and at least one eardrum stimulating member described in more detail below. The hearing aid  122  generally receives sound waves conducted from the outer ear  110  through the ear canal  112 , converts the sound waves into electrical or electromagnetic signals, and converts the electrical signals into mechanical motion, which is typically called a feed-forward system. The mechanical motion is used to impact the tympanic membrane  114 , and/or portions of the middle and inner ear, to vibrate the ossicular chain  115 , specifically the malleus  118 , the incus  117 , and the stapes  116 . These three bones in the ossicular chain  115  act as a set of levers that amplify the amplitude of the vibrations received by the tympanic membrane  114 . The stapes  116  is coupled to the entrance of a spiral structure known as the cochlea  120  that contains an inner ear fluid. The mechanical vibrations of stapes  116  cause the fluid to develop fluid impulses that cause small hair-like cells (not shown) in the cochlea  120  to vibrate. The vibrations are transformed into electrical impulses, which are transmitted to neuro-pathways in the hearing center of the brain resulting in the perception of sound. 
       FIG.  2    is a schematic plan view of the tympanic membrane  114  (a right tympanic membrane is shown as an example). The tympanic membrane  114  is generally an oval shape, which is slightly drawn inwards at its center, called the umbo  202 , which is where the handle of malleus (shown in  FIG.  1    and described above) is attached. The tympanic membrane is conceptually divided into four quadrants: the anterior superior quadrant  204 , the anterior inferior quadrant  206 , the posterior inferior quadrant  208 , and the posterior superior quadrant  210 . 
     Compact Hearing Aids and Components Thereof 
     The present disclosure relates to compact hearings aids, components thereof, and support systems therefore. The embodiments described herein provide exemplary configurations of compact hearing aids contemplated by the present disclosure. However, any other suitable configurations for hearing aids that modulate the velocity or the position of the tympanic membrane, by direct or indirect modulation, are also contemplated. The embodiments that follow discuss inserting the disclosed compact hearing aids through the tympanic membrane, as an example; however, the compact hearing aids are also disposable in other locations within the ear. 
       FIG.  3    is a schematic perspective view of a compact hearing aid  300 .  FIG.  4    is a cross-sectional view of the compact hearing aid  300  of  FIG.  3   . As shown in  FIGS.  3  and  4   , the compact hearing aid  300  is encompassed in a housing  301 , which includes two flange portions  302  coupled by a connecting portion  304 . When implanted, the two flange portions  302  are positioned on opposite sides of the tympanic membrane (i.e., one flange portion is in the outer ear and the other portion is in the middle ear) and the connecting portion  304 , shown as a narrow tube as an example, transverses the tympanic membrane. The connecting portion  304  is generally positioned along the center axis of the compact hearing aid  300  or parallel to the center axis of the compact hearing aid  300 . 
     As used herein the term flange refers to a portion of the disclosed compact hearing aids, which is lateral or peripheral to a central portion thereof, such as the connecting portion  304 . 
     The one or more flanges and the connecting member generally make up the body of the compact hearing aid. As used herein, the term body generally refers to the one or more flanges and the connecting portion as a unit. 
     As shown in  FIG.  4   , the compact hearing aid  300  is enclosed by the housing  301 , which houses the various components of the compact hearing aid  300 . The various components generally include at least a sensor  408 , such as a microphone configured to detect the sound to be processed, a mass which is shown as an energy source  410 , an actuator  412  configured to convert electrical signals into mechanical motion, and a processor  414  configured to aid with signal processing and power conversion by modifying electrical signals and transmitting the electrical signals to the at least one actuator, as well as to drive the actuator  412  to move the mass, which is the energy source  410  in this example. Together, the mass and the at least one actuator make up a tympanic membrane actuation assembly. In embodiments in which the energy source  410  is a rechargeable energy source, the compact hearing aid  300  generally also includes a recharging circuit  416 . 
     The sensor  408  is generally fixed within the housing  301  and is configured to receive the sound to be amplified by the compact hearing aid  300  and convert the sound waves or acoustic signals into electrical or electromagnetic signals. The present disclosure contemplates a microphone as the sensor  408  as an example; however, it is contemplated that the sensor  408  is generally any suitable sensor. Suitable sensors include, but are not limited to, high sensitivity microphones, piezoelectric micro-electro-mechanical systems (MEMS) microphones, electrostatic microphones, accelerometers, gyroscopes, and optical sensors. Other suitable sensors include sensors, which may be used to sense otoacoustic emissions (OAEs) or pressures to diagnose ear infections, or other changes in the user or in the performance and device health of the compact hearing aid  300  itself. 
     While one sensor  408 , which is a microphone, is shown as an example, further embodiments of the compact hearing aids described herein include multiple microphones or other sensors, which may be disposed about the lateral aspect of the compact hearing aid, about the medial aspect of the compact hearing aid, or on both the medial and lateral aspects of the compact hearing aid. In yet further embodiments, one microphone, such as sensor  408  is disposed in the compact hearing aid, and one or more other microphones are disposed elsewhere, such as in the ear canal. In such embodiments, the one or more external microphones are directly connected or, or otherwise communicate with, the compact hearing aid  300 . 
     In another embodiment, the sensor  408  may be disposed outside of the housing. In another embodiment, the compact hearing aid  300  may include a second actuator to ensure that the sensor  408  does not move with the housing or the first actuator. In yet another embodiment, the compact hearing aid  300  may further include a passive mechanical coupler to isolate the sensor  408  from the movement of the housing or the first actuator. 
     The mass is any suitable mass material, component, or combination of components, which may be actuated to modulate the velocity or the position of the tympanic membrane, and may include any suitable number of portions, such as a first portion and a second portion. The mass is generally between about 5 milligrams (mg) and about 40 mg in total. For example, in embodiments comprising a first portion and a second portion, each portion being a battery, the weight is generally between about 10 mg per battery and about 15 mg per battery (totaling between about 20 mg and about 30 mg, respectively). 
     The energy source  410  is generally any suitable energy source of any suitable configuration, such as a single mass, a thin film battery having multiple, vertically-stacked layers (for example, between 5-20 layers), a radio thermal generator, a super capacitor, a thick film battery, or a traditional lithium (Li) ion battery. As shown in  FIG.  4   , the mass is the energy source  410 , which is dumbbell shaped and disposed centrally within the compact hearing aid  300 . In such an embodiment, the energy source  410  itself can be used as the mass to modulate the velocity or the position of the tympanic membrane. In further embodiments, the energy source  410  is disposed medially or laterally within the compact hearing aid and on one side of the tympanic membrane. In yet further embodiments, such as  FIGS.  13 ,  14 ,  16 A -C,  17 , and  18 , one or more mass portions, such as batteries, are disposed on both the medial and lateral sides of the tympanic membrane and may be connected by a connection member disposed in the housing  301  that traverses the tympanic membrane. In still further embodiments, an energy source and a counter mass, which are connected across the tympanic membrane, are used. The counter mass is generally an inert or inactive mass. 
     In one embodiment, the diameter of the energy source  410  is less than or equal to 2.5 millimeters (mm) and the height is less than or equal to 1.5 mm. The mass of the energy source  410  is selected to maximize the safety of holding the compact hearing aid in the tympanic membrane and/or based on a passive noise transmission attenuation level, for example less than or equal to 10 decibels (dB). In one embodiment, the mass is generally less than or equal to about 15 milligrams (mg). As described below, the energy source  410  is generally rechargeable. In such embodiments, the charging time is generally less than or equal to about 3 hours and can be charged more than 1,000 times. 
     The actuator  412  is generally any actuator mechanism, or any plurality of actuator mechanisms, suitable to convert the electrical signals into mechanical motion by moving the mass such that the mass modulates the velocity or the position of the tympanic membrane, and may be disposed on the medial side, the lateral side, both sides of the tympanic membrane, or across the tympanic membrane. The actuator  412  is configured to push the mass, and to retrieve, or pull, the mass, relative to the coupling to the tympanic membrane. 
       FIG.  5    is a plan view of an actuator  500  according to one embodiment, which may be used as the actuator  412 . The actuator  500  includes at least an outer ring  502  and an inner ring  504 , the outer ring  502  being connected to the housing  301  and the inner ring  504  being connected to the mass, such as the energy source  410 . The outer ring  502  has a plurality of piezoelectric actuators  506  that can be excited to create the force needed to modulate the inner ring  504  axially and to ultimately modulate the velocity or the position of the tympanic membrane. In another embodiment, the plurality of piezoelectric actuators  506  are individually addressable to provide non-axial modulation of the velocity or the position of the tympanic membrane. 
       FIG.  6    is a perspective side view of an actuator  600  according to another embodiment, which may be used as the actuator  412 . The actuator  600  includes a first disk  602  and a second disk  604 , which are coupled together by a plurality of piezoelectric actuators  606  sandwiched therebetween. At least one of the first disk  602  or the second disk  604  is movable to modulate the velocity or the position of the tympanic membrane. In another embodiment, the plurality of piezoelectric actuators  606  are individually addressable to provide non-axial modulation of the velocity or the position of the tympanic membrane. 
       FIG.  13    is a cross-sectional view of a compact hearing aid, such as compact hearing aid  300 , having an alternative embodiment of an actuator. In the embodiment shown in  FIG.  13   , the actuator is a piezoelectric stack actuator  1320  that actuates linearly. The base  1324  of the piezoelectric stack actuator  1320  is fixed. As shown, one or more connecting members  1322 , shown as disposed around the outside of the piezoelectric stack actuator  1320 , connect a first mass  1328  to a trailing mass  1326 . The first mass  1328  is displaced by the piezoelectric stack actuator  1320  and the trailing mass  1326  generally follows the movement of the first mass  1328  to move the masses in phase. 
       FIG.  14    is a cross-sectional view of a compact hearing aid, such as the compact hearing aid  300 , having an alternative embodiment of an actuator. In the embodiment shown in  FIG.  14   , the actuator is a piezoelectric microtube  1420 . The base  1424  of the piezoelectric microtube  1420  is fixed. In operation, the piezoelectric microtube  1420  lengthens linearly to displace the first mass  1426 . One or more connecting members  1422  connect the first mass  1426  and the second mass  1428 . The one or more connecting members  1422  lie in an inner diameter of piezoelectric microtube  1420 . 
     In still further embodiments, the actuator  412  is a linear actuator. For example, the actuator  412  may be a voice coil having a central mass, generally a magnet, with an outer coil wrapped there around, which modulates the force on the mass by energizing the outer coil. Alternatively, the voice coil may be centrally disposed with the magnet disposed therearound. The linear actuator may traverse the tympanic membrane within the compact hearing aid, which when energized, oscillates and creates a modulating force to the tympanic membrane. In another embodiment, the actuator  412  includes a plurality of actuators coupled to the housing  301  and/or the energy source  410 . In yet another embodiment, the actuator  412  is a plurality of concentric actuators that create linear movement. In yet another embodiment, the actuator  412  is a rotary actuator that creates a wave that extends radially from the compact hearing aid. In yet another embodiment, the actuator  412  includes a piezo MEMS device or an electrostatic MEMS device with a stepper motor, for example. In yet another embodiment, an actuator may be formed through the combination of two or more of the above-mentioned actuators. 
     As discussed herein, the disclosed compact hearing aids include one or more actuators. When more than one actuator is used, all of the actuators may be the same type of actuator or more than one type of actuator. When more than one type of actuator is used, the stimulation of the actuators may be in different or similar planes. In one embodiment, the different types of actuators are configured to actuate in different planes at the same time, for example, to grow in length and/or diameter. Additionally, and as discussed further below, the actuator may utilize an impedance matching component, such as a MEMs lever arm depending on the energy and displacement ranges needed to improve the user&#39;s hearing. 
     As shown in  FIGS.  4 ,  13 , and  14   , the compact hearing aid  300  may also include a movement mechanism  418 , such as bearings or a linear slide, which confines the movement of the mass to the direction of the actuation. 
     The Operation of the Hearing Aid 
     The processor  414 , which is generally an Application Specific Integrated Circuit (ASIC) chip, takes an electrical signal from the sensor  408  that represents the acoustic signals and converts the signals into an electrical signal to drive the actuator  412  and move the mass (e.g., the energy source  410 ) to modulate the position of the tympanic membrane and thus provide impulses to the user&#39;s brain. The mass generally moves a distance of less than or equal to about one millimeter. The direct or indirect modulation of the position of the tympanic membrane improves the hearing of the user. 
     In addition to converting the signals for modulating the mass, the processor  414  may also bias the sensor  408 , and provide safety functions, such as internal temperature and current monitoring. 
     In some embodiments, the processor  414  encompasses the safety circuitry for the energy source  410 , including for appropriately charging and discharging the energy source  410  safely and efficiently. 
     In even further embodiments, the processor  414  also performs communication functions such that the compact hearing aid can send information to, and receive information from, the external world. For example, the processor  414  generally includes circuitry allowing the compact hearing aid to communicate information about the state of the compact hearing aid, and even the state of the user&#39;s ear, to an external recipient. 
     In even further embodiments, the processor  414  is configured to modify acoustic input to allow for frequency shifting. This frequency shifting processing is useful to optimize the mechanical output, address various frequency responses and transfer functions ultimately to provide the user a superior acoustic experience. For example, certain frequencies or nodes that the device may miss, which have been preidentified, may be captured and shifted so that the user will hear the missed frequency at a different, shifted frequency. 
       FIG.  12    depicts a block diagram of an ASIC processor  1200 . The ASIC processor  1200  may be used as the processor  414 . The ASIC processor  1200  generally includes a wireless communications component  1202 , a safety circuit component  1204 , a nonvolatile memory component  1206 , a microphone preamplifier component  1208 , a signal processing component  1210 , an actuator driver component  1212 , an energy source management component  1214 , a power supply component  1216 , and a wireless power component  1218 . Wireless communications include, but are not limited to, optical, acoustic, and radio frequency communications. 
     In one embodiment, the ASIC processor  1200  uses analog signal processing to reduce power needs and minimize digital components. Additionally, the ASIC processor  1200  may be configured to minimize power consumption via programming and/or estimating responses, while maintaining acceptable processing. In another embodiment, the ASIC processor  1200  may be configured to perform frequency communication and/or registration via an audio device, such as a smart phone. For example, the ASIC processor  1200  may be configured to turn the compact hearing aid on and off via an acoustic profile signature. The ASIC processor  1200  may also be configured to change the intensity mode, for example by controlling the amplitude when in uncomfortable acoustic environments, using the acoustic profile signature, to limit amplitude of all frequencies, and/or to provide noise cancellation. Even further, the ASIC processor  1200  may be configured to recognize emergency tones that automatically turn the compact hearing aid on, such as fire alarms, door bells, and glass breaking sounds. 
     In further embodiments, the ASIC processor  1200  uses digital signal processing. 
     In another embodiment, the ASIC processor  1200  is wirelessly controlled by radiofrequency (RF) signals. The RF signals may be used to turn the compact hearing aid on and off, to change the intensity mode to control amplitude in uncomfortable acoustic environments, and to provide for tuning and verification tone responses for diagnostics. 
     The ASIC processor  1200  may also be configured to filter certain frequencies. For example, the disclosed compact hearing aids may further or alternatively include a feed-forward system to control feedback by changing frequencies of certain ranges of input to avoid certain resonance frequencies. The disclosed compact hearing aids may also or alternatively include a system with learning algorithms to adjust frequency responses when unique environments produce unique resonance frequencies. OAEs are sounds produced by the inner ear. More specifically, there are hair cells in the inner ear that respond to signals by vibrating. The vibration produces a very quiet sound that reverberates back into the middle ear. It is thought that OAEs help to selectively amplify certain frequencies. Similarly, the compact hearing aids disclosed herein are also configurable to produce a low decibel and patentable frequency signal that will help to amplify the incoming sounds. This extra background sound will help with improving the signal-to-noise (STN) ratio, or it will be uniquely helpful at certain frequencies. This background sound could be a simple single frequency sound, it could be a single complex sound made up of multiple different frequencies, or it could be several sounds, which are fractions of a second apart, or it could generate any of these sounds at specific times depending on the frequency being processed. 
     The disclosed compact hearing aids are also configurable to self-diagnose by recognizing the OAEs and making adjustments in the device itself to optimize hearing for that particular user. 
     Additionally, the disclosed compact hearing aids produce an output, to which the inner ear responds and produces a unique OAE, which is correlated with the degree of hearing loss at those frequencies. 
     Additional Device Components and Configurations 
     In the embodiment shown in  FIG.  4   , the compact hearing aid  300  includes a separate recharging circuit  416 ; however, as discussed above, in other embodiments, much, and sometimes all, of the recharging circuit can be included in the processor  414 . The recharging circuit  416  recharges the energy source  410 . 
     In one embodiment, one or more coil arrays for recharging are disposed in or about the flange(s). In another embodiment, one or more coil arrays for recharging are disposed in or about the lateral portion of the compact hearing aid. In yet another embodiment, one or more coil arrays for recharging are disposed in or about the medial portion of the compact hearing aid. In yet another embodiment, one or more coil arrays for recharging are disposed in both the medial and lateral portions of the compact hearing aid. In yet another embodiment, one or more of the coil arrays for recharging may be the same coil that powers the voice coil actuator described above. 
       FIGS.  16 A- 16 C  depict an alternative embodiment of a compact hearing aid  1600 . The compact hearing aid  1600  includes an enclosure housing  1601  that houses at least a microphone  1608 , a first mass, shown as a first battery  1626 , as an example, a second mass, shown as a second battery  1628 , as an example, coupled to the first battery  1626  by a connecting member  1621 , and a processor  1614 . The connecting member  1621  includes, or is surrounded by, an actuator  1620 . The actuator  1620  is generally a tubular or cylindrical stacked piezoelectric actuator having a hole therein to allow the connecting member  1621  to pass therethrough. The height of the actuator  1620  is generally between about 1 mm and about 4 mm, and the outer diameter of the actuator  1620  is generally between about 1 mm and about 2 mm. 
     The compact hearing aid  1600  also includes a recharging coil antenna  1616  disposed around the microphone  1608 . The recharging coil antenna  1616  is used to recharge the first battery  1626  and the second battery  1628  daily. When positioned within the ear, the first battery  1626  and the second battery  1628  are disposed on opposite sides (i.e., the medial and lateral sides) of the tympanic membrane and the connecting member  1621  is disposed through the tympanic membrane. 
     Factors considered in the design of the various components, such as the actuator, of the compact hearing aids described herein are the amount of force to be applied to, and the amount of displacement of, the tympanic membrane to improve the user&#39;s hearing. The amount of force may vary based on the modulating mass or masses of between about 20 mg and about 30 mg, between about 0.05 microns and about 5.0 microns of displacement with a force of between about 0.001 Newtons (N) and about 0.05 N, across the audible frequency range. 
     As shown in  FIG.  17   , the compact hearing aid includes an actuation assembly  1700 , which may also include a displacement multiplier  1725  in conjunction with the actuator  1723  to amplify the actuation of the first mass, shown as a first battery  1726 , as an example, and the second mass, shown as a second battery  1728 , as an example. The displacement multiplier  1725  is shown as a piezo coupling arm lever, as an example. The arm lever displacement multiplier  1725  includes an actuator leg portion, a pivot on case portion, and a mass, shown as a battery, leg portion. As shown in  FIG.  19   , the actuation assembly  1900  may also include a fixed coupling  1925  in conjunction with the actuator  1923 . The fixed coupling  1925  is shown as a fixed coupling to the top of the actuator, as an example. As shown in  FIG.  20   , the actuation assembly  2000  may also include a rigid coupler  2025  in conjunction with the actuator  2023 . The rigid coupler  2025  is shown as a rigid coupler between the first battery  2026  and the second battery  2028  and positioned around the outside of the actuator  2023 , as an example. 
     As shown in  FIGS.  21  and  22   , the various piezo couplings, including the arm lever displacement multiplier, the fixed coupling, and the rigid coupler, may include any suitable number of components surrounding or otherwise coupled to the actuator  2123  and  2223 , respectively. The actuator  2123  is shown as a rectangular prism as an example, and the actuator  2223  is shown as a cylindrical tube as an example. The actuators  2123 ,  2223  are surrounded by a plurality of any suitable number and combination of rigid coupler portions  2131 ,  2231 , fixed coupling portions  2135 ,  2235 , and arm lever displacement multiplier portions  2137 ,  2237 . 
     In addition to the aforementioned components, the disclosed compact hearing aids may also include additional components, such as sensors for detecting a change in the biological conditions of the ear, for example, infections, inflammation, scar tissue, or epithelial cell migration. 
     The housing  301  is generally any suitable covering which encloses and provides a sealed compartment for the device components. Suitable casings including, for example, biocompatible materials, such as silicon, fluoropolymers, polyethylene, stainless steel, and titanium. The housing  301  is either a solid or a porous material. In one embodiment, the housing  301  has micro holes to allow for venting. In another embodiment, the housing  301  is solid such that it does not have any venting holes therethrough. In another embodiment, the housing  301  is solid such that it does not have any venting holes therethrough and utilizes dead space to allow for compression created by internal movement. In some embodiments, the housing  301  includes linear channels to allow for internal pressure balancing due to internal movement of the actuator and mass (e.g., the battery). The linear channels also provide compensation for epithelial migration about the compact hearing aid  300 . Even further, the linear channels provide mechanical benefits, such as improved stabilization. 
       FIG.  18    depicts a schematic cross-sectional view of a compact hearing aid  1800 . The compact hearing aid  1800  includes a housing  1801  which encloses a stack of components, which includes a microphone  1808 , a processor  1814 , a first portion  1826 , shown as a first battery, a second portion  1828 , shown as a second battery, and a connecting member  1820  having an actuator disposed therein. 
     The housing  1801  is between about 5 mm and about 10 mm in length, such as about 6 mm. The housing  1801  generally has two diameters, a first diameter  1815  and a second diameter  1817 . The first diameter  1815 , which generally corresponds to the flanged portions that rest on either side of the tympanic membrane, is between about 1 mm and about 5 mm, such as about 3 mm. The second diameter  1817 , which corresponds to the portion of the compact hearing aid  1800  to be disposed through the tympanic membrane, is between about 0.5 mm and about 3 mm, such as about 1.5 mm. The notched portion  1829 , in which the tympanic membrane is to be disposed is generally between about 0.15 mm and about 0.5 mm, such as about 0.25 mm, to provide sufficient space for the tympanic membrane without pinching the tympanic membrane such that it would cause necrosis. 
     Each of the microphone  1808  and the processor  1814  is between about 0.25 mm and about 1.0 mm thick, such as about 0.5 mm. Each of the first portion  1826 , and the second portion  1828  is between about 1 mm and about 2 mm in height, such as about 1.5 mm, and has an outer diameter of between about 2 mm and about 3 mm, such as about 2.5 mm. The connecting member  1820 , having an actuator disposed therein in some embodiments, or coupled thereto, is between about 0.5 mm and about 3 mm in height, such as about 1 mm, and has an outer diameter between about 0.5 mm and about 2 mm, such as about 1 mm. Similarly, in some embodiments, the actuator may be between about 0.5 mm and about 3 mm in height, such as about 1 mm, and have an outer diameter between about 0.5 mm and about 2 mm, such as about 1 mm. 
     As discussed above, the compact hearing aid can be of any suitable size and shape with components of various size and shape; however, each configuration generally requires the same various components, for example, the microphone, energy source, actuator, and processor. 
       FIG.  7    is a schematic perspective view of an alternative embodiment of a compact hearing aid  700 . As shown in  FIG.  7   , at least one flange  702 , generally the medial flange, is interrupted by a pie-shaped notch  704  therein. The notch  704  is useful for insertion of the compact hearing aid  700  through the tympanic membrane because the notch  704  acts as an Archimedes screw, making it easier to fit the flange  702  through a smaller incision. 
       FIG.  8    is a schematic perspective view of an alternative embodiment of a compact hearing aid  800 . The compact hearing aid  800  includes at least one flange  802 , generally the medial flange, which is conical and acts as a dilator when inserted through an incision in the tympanic membrane. 
     In further embodiments, at least one of the first flange and the second flange of the compact hearing aid is otherwise tapered from a first end to a second end thereof, such that the first flange or the second flange acts as a dilator when inserted through an incision in the tympanic membrane. 
       FIGS.  9 A- 9 C  depict various views of an alternative embodiment of a compact hearing aid  900 . The compact hearing aid  900  includes a first flange  902  and a second flange  904 . The first flange  902  has a plurality of first flange tabs  906  coupled thereto, and the second flange  904  has a plurality of second flange tabs  908  coupled thereto. The plurality of second flange tabs  908  are offset from the plurality of first flange tabs  906 . As shown in  FIG.  9 B , and described further below, the first flange tabs  906  and the second flange tabs  908  generally lie flat against the compact hearing aid  900  until after the compact hearing aid  900  has been inserted through the tympanic membrane. After the compact hearing aid  900  is inserted, the plurality of first flange tabs  906  and/or the plurality of second flange tabs  908  are opened such that they lie parallel to the surface of the tympanic membrane to stabilize the compact hearing aid  900 , as shown in  FIG.  9 C . 
     The mounting region of the disclosed compact hearing aids generally includes one or more flanges, such as the first flange  902  and the second flange  904 , which are positioned to optimize energy transfer to the tympanic membrane, with a space  909  therebetween configured for the tympanic membrane to be disposed therein. The mounting region provides for retention of the compact hearing aid, such as compact hearing aid  900 , in the tympanic membrane. In addition, the mounting region provides for balance and stabilization of the compact hearing aid  900  in the tympanic membrane. In further embodiments, the one or more flanges may deliver actuation or modulation to the tympanic membrane. In some embodiments, the one or more flanges contain a charging coil or charging array. In addition, in some embodiments, the one or more flanges include predesigned features to provide offset forces to avoid pinching or clamping of the tympanic membrane since such pinching or clamping often causes necrosis of, or a hole in, the tympanic membrane. 
     In further embodiments, at least one of the first flange and the second flange is compressible and can be deployed or released into its final shape or position once inserted through the tympanic membrane. 
     The above-described embodiments provide exemplary shapes and configurations of the one or more flanges. However, the present disclosure contemplates further shapes and configurations, including but not limited to, circular flanges resembling a top hat, circular flanges resembling a top hat having a brim turned up about the outer edge, a skirt that flairs away from the body that curls up around its edges, a circular flange that is undercut on the side that faces the tympanic membrane, while the outer ring is turned upward distributing the clamping force to the outer rim of the flange, and a flange that is created by a micro-wire form that is covered by a thin film of material or polymer and can also be used as the recharging coil for inductive recharging. In some embodiments, the surface of the brim may a multiplane surface, such as a wavy surface or a stepped surface. 
     In some embodiments, the flanges which stabilize the compact hearing aid are juxtaposed across the tympanic membrane to avoid opposing pressure maintaining vascular profusion about the tympanic membrane and avoiding necrosis. Such flanges generally include tabs arranged around the circumference of the flange that individually flare away from the flange and body of the compact hearing aid. The tabs can be various shapes, including but not limited to, pie shaped, lobes, dual lobes, or clover shaped. 
     In yet another embodiment, the mounting region includes an array of intermittent flanges that is undercut on the side that faces the tympanic membrane, while the outer edge of the intermittent flanges may be turned upward to distribute the force to the outer rim of the flange. The array can be placed on the medial and lateral sides to sandwich the tympanic membrane therebetween, or offset radially to ensure the tympanic membrane is not pinched between stabilizing flanges. 
     In further embodiments, the flanges are designed to stabilize the compact hearing aid and are positioned to, or have features to, mitigate the challenges of epithelial migration on the lateral side of the tympanic membrane. The flanges can be juxtaposed with retention and stabilizing features on the medial side. Suitable features include, but are not limited to, bump patterning, bi-lateral hatching, linear tracks or channels, axial tracks, patterning of tear drop shaped raised portions, and boat hull-shaped configurations. In still further embodiments, these features may additionally or alternatively be patterned on other portions of the disclosed compact hearing aids, such as the body. 
     In still further embodiments, at least one of the one or more flanges includes an actuator component, which extends from the compact hearing aid to modulate the malleus or umbo directly. In still further embodiments, an actuator may extend from other portions of the compact hearing aid, such as the body, to modulate the malleus or umbo directly. 
     The flanges disclosed herein, alone or in any combination, may interact with the body of the compact hearing aid and/or with the tympanic membrane in any suitable manner. 
       FIGS.  23 A- 23 D  depict an alternative embodiment of a compact hearing aid  2300 . The compact hearing aid  2300  is similar to other embodiments described herein, but utilizes bending mode actuators  2322 ,  2324  to actuate one or more masses for modulation of velocity and/or position of a tympanic membrane. 
     Note that, herein, a medial end, side, or surface of a component refers to the end, side, or surface that is closer to the tympanic membrane when implanted. On the other hand, the lateral end, side, or surface of a component refers to the end, side, or surface that is further from the tympanic membrane when implanted. 
     The compact hearing aid  2300  generally includes a first enclosure housing  2301  having a first medial wall  2350  (shown in  FIG.  23 B ) and a first lateral shell  2370 . Together, the medial wall  2350  and lateral shell  2370  encase at least a microphone  2308 , a processor  2314  coupled to the microphone  2308 , a first active or inactive mass, shown as a first battery  2326  coupled to the processor  2314  in this example, and first actuator  2322  coupled to the first battery  2326 . In certain embodiments, a recharging coil antenna  2316  is disposed around the microphone  2308  to enable daily recharging of the compact hearing aid  2300 . In certain embodiments, the recharging coil antenna  2316  and the microphone  2308  are independent of the first battery  2326 , which is indirectly coupled to the first medial wall  2350 . The compact hearing aid  2300  further includes a second enclosure housing  2302  having a second medial wall  2352  (shown in  FIG.  23 B ) and a second lateral shell  2372  that together encase at least a second active or inactive mass, shown as a second battery  2328 , and second actuator  2324  coupled to the second battery  2328 . The first enclosure housing  2301  is coupled to the second enclosure housing  2302  by a connecting member  2320  disposed between the adjacent medial walls  2350 ,  2352  of the first and second enclosure housings  2301 ,  2302 , respectively. 
     When implanted, the medial walls  2350 ,  2352 , which may be planar in morphology, are positioned on and contacting (i.e., disposed against) opposing sides of the tympanic membrane while the connecting member  2320 , shown as a tubular-like structure as an example, transverses the tympanic membrane along or parallel to a central axis of the compact hearing aid  2300 . In addition to providing mechanical support, the connecting member  2320  enables routing of electrical signal connections between the enclosure housings  2301 ,  2302  (e.g., for recharging and actuation of the masses). 
     Note that although the masses in  FIGS.  23 A- 23 D  are depicted and described as batteries  2326 ,  2328 , the bending mode actuators  2322 ,  2324  may modulate any suitable type of mass or mass material other than a battery in certain embodiments. For example, the masses may be any suitable mass material, component, or combination of components, which may be actuated to modulate the velocity or the position of the tympanic membrane. 
     As shown in  FIGS.  23 A- 23 D , the actuators  2322 ,  2324  are indirectly coupled to the medial walls  2350 ,  2352  within the enclosure housings  2301 ,  2302 , respectively, and on opposing sides of the connecting member  2320 . In certain other embodiments, however, the actuators  2322 ,  2324  are indirectly coupled to the lateral shells  2370 ,  2372 , which may have a dome-like morphology. The actuators  2322 ,  2324  are each held in place by one or more brackets  2354  (shown in  FIG.  23 B ) extending from the medial walls  2350 ,  2352  or lateral shells  2370 ,  2372 , which provide slots in which the actuators are secured at distal ends thereof. The brackets  2354  further provide clearances  2356  between each actuator  2322 ,  2324  and the corresponding medial wall  2350 ,  2352  to facilitate deflection of the actuators during operation. As shown, the actuators  2322 ,  2324  are further indirectly coupled to at least the batteries  2326 ,  2328 , via extensions  2380 ,  2382 , respectively, thus enabling internal displacement of the batteries by the actuators within each enclosure housing  2301 ,  2302 . 
     An enlarged view of the second actuator  2324  within the second enclosure housing  2302  is depicted in  FIG.  23 C  for reference. Unless otherwise specified, description of the components of the second actuator  2324  and second enclosure housing  2302  may apply to the first actuator  2322  and first enclosure housing  2301 . 
     As described above, the second actuator  2324  is a bending mode actuator, such as a unimorph-type actuator, bimorph-type actuator, dome-type actuator, or the like. For purposes of clarity and not to be limiting, the second actuator  2324  is herein depicted and described as a unimorph-type actuator having at least one inactive layer  2360  and at least one active layer  2362 . Each of the inactive and active layers  2360 ,  2362  comprises a thin film-like layer configured to be controllably deformed upon application of an electric field to the active layer. Accordingly, one or more electrodes  2364  may be disposed at either end of the second actuator  2324  and contacting at least the active layer  2362 . In certain examples, the one or more electrodes  2364  are formed of gold (Au), platinum (Pt), copper (Cu), or any other suitable conductive material. 
     As shown in  FIG.  23 C , the inactive layer  2360  of actuator  2324  is disposed between the active layer  2362  and the medial wall  2352  of enclosure housing  2302 . The medial wall  2352  is generally less than 1 mm thick and is formed of a biocompatible material, similar to the lateral shell  2372 . Brackets  2354  extend from the medial wall  2352 , or the lateral shell  2372 , and at distal ends of inactive layer  2360  to clamp the inactive layer in place while also providing clearance  2356  to facilitate deformation of the actuator. In certain embodiments, the inactive layer  2360  is formed of titanium (Ti) or titanium oxide (TiO 2 ) and have thicknesses between about 0.02 mm and about 0.1 mm, such as between about 0.02 mm and about 0.03 mm, such as about 0.02 mm. 
     The active layer  2362  is coupled to the inactive layer  2360  opposite of the medial wall  2352  and generally has a thickness greater than that of the inactive layer, such as between about 0.05 mm and about 0.2 mm, such as between about 0.065 mm and about 0.085 mm, such as about 0.075 mm. The active layer  2362  may be formed of a piezoelectric-type material having a perovskite crystal structure, such as lead zirconate titanate (PZT), barium titanate (BaTiO 3 ), strontium titanate (SrTiO 3 ), or other ferroelectric materials. In certain embodiments, the inactive layer  2360  and the active layer  2362  each have a length between about 1 mm and about 4 mm, such as between about 2 mm and about 3 mm, and a width less than about 3 mm, such as less than about 2 mm. 
     As previously mentioned, the active layer  2362  is also indirectly coupled to at least battery  2328  via extension  2382  (active layer  2362  within the first enclosure housing  2301  is coupled to at least battery  2326  via extension  2380 ). The extensions  2380 ,  2382  may be similar in structure and material to the connecting member  2320  disposed between medial walls  2350 ,  2352 . In certain embodiments, as depicted in  FIGS.  23 A- 23 C , the extensions  2380 ,  2382  are coupled between aligned and centrally-disposed positions on lateral surfaces of the active layers  2362  and medial surfaces of the batteries  2326  and  2328 , thus facilitating axial motion of the batteries during operation. In such embodiments, the inactive layers  2360  may be secured to the medial walls  2350 ,  2352 , or lateral shells  2370 ,  2371 , by two brackets  2354  at opposing ends thereof. In certain other embodiments, however, the extensions  2380 ,  2382  are coupled between oblique (e.g., non-central) and non-axial (e.g., unaligned) positions on the lateral surfaces of the active layers  2362  and medial surfaces of the batteries  2326  and  2328 , as shown in  FIG.  23 D . In such embodiments, the coupling of the active layers  2362  and batteries  2326 ,  2328  facilitates rotational (e.g., nonlinear) motion of the batteries during operation. Accordingly, the inactive layers  2360  may be secured to the medial walls  2350 ,  2352  or lateral shells  2370 ,  2371  by only one bracket  2354  at a distal end of each inactive layer  2360 , enabling greater deflection of the actuators  2322 ,  2324 . In some examples, the single bracket  2354  is secured to each inactive layer  2360  at an end opposite the end of the active layer  2362  coupled to the extension  2380  or  2382 . 
     In operation, the microphone  2308  or any other suitable sensor receives a sound to be amplified and the processor  2314  converts the soundwaves or acoustic signals into an electrical signal that is applied to the first and/or second actuators  2322 ,  2324 . The electrical signal is transmitted to the active layers  2362  thereof by the one or more electrodes  2364 , causing the active layers to morph (e.g., deform) in a desired direction. For example, the active layers  2362  of the first and second actuators  2322 ,  2324  may be similarly or inversely energized to morph in a similar or inverse directions as desired. The deformation of the active layers  2362  modulates the positions of the batteries  2326  or  2328  (e.g., masses) relative to the tympanic membrane and connecting member  2320  disposed therebetween, thereby modulating the tympanic membrane which provides impulses to the user&#39;s brain via the ossicular chain and cochlea. 
     In certain embodiments, the active layers  2362  have a capacitance of less than about 300 pico-Farads (pF), such as less than about 200 pF. The active layers  2362  may be driven by a 40 volt (V) alternating current (AC) to a frequency between about 7500 to about 10500 Hertz (Hz), such as between about 8000 to about 10000 Hz. In further embodiments, each of the active layers  2362  displaces the medial walls  2350 ,  2352  and/or the batteries  2326 ,  2328  by a distance of about 1 μm to about 5 μm, such as about 2 μm, and produces a blocking force between about 0.02 to about 0.1 N, such as between about 0.04 N to about 0.07 N. 
     Utilization of the compact hearing aid  2300  depicted in  FIGS.  23 A- 23 D  may facilitate more controlled tympanic membrane modulation as the first and second actuators  2322 ,  2324  enable better utilization of hearing aid internal mass. For example, including two separate actuators  2322 ,  2324  enables each mass (e.g., battery  2326  or  2328 ) to be modulated independently of the other, thereby reducing energy losses resulting from modulating both masses together. Furthermore, the structure and bending mode functionality of the actuators  2322 ,  2324  enables free movement of internal components, such as the masses, within the enclosure housings  2301 ,  2302 . Thus, the actuators  2322 ,  2324  may provide a more stable internal environment with a reduction of undesired micro-movement of the connecting member  2320  and connections disposed therein. 
       FIGS.  24 A- 24 F  depict yet another embodiment of a compact hearing aid  2400  that utilizes bending mode (e.g., unimorph-type) actuators  2422 ,  2424  for modulation of velocity and/or position of a tympanic membrane. The hearing aid  2400  is substantially similar to hearing aid  2300 , and thus, similar components between the hearing aid  2400  and the hearing aid  2300  have been labelled with the same reference numerals for clarity. 
     Unlike the hearing aid  2300 , the masses of hearing aid  2400 , shown as batteries  2326 ,  2328  in this example, are not directly coupled to the actuators  2422 ,  2424 , and are instead directly or indirectly coupled to the lateral shells  2370 ,  2372 , respectively. Accordingly, the batteries  2326 ,  2328  in  FIGS.  24 A- 24 C  are shown separated from the actuators  2422 ,  2424  by clearances  2446 . In certain embodiments, the first battery  2326  is directly and/or indirectly coupled to the first lateral shell  2370  via the microphone  2308  and/or the processor  2314 . In such embodiments, the microphone  2308  and/or the processor  2314  may be attached to the lateral shell  2370  via any suitable coupling mechanism, such as a bonding adhesive or other support structure. In certain embodiments, the second battery  2328  is directly coupled to the second enclosure housing  2302  opposite of the medial wall  2352 . Similar to the microphone  2308  and processor  2314 , the second battery  2328  may be attached to the second lateral shell  2372  via a suitable coupling mechanism, such as a bonding adhesive or other support structure. 
     Furthermore, the first and second actuators  2422 ,  2424  of the hearing aid  2400  are formed of a flexible membrane such as polymer or silicone and are disposed along or integrated with the medial walls  2350 ,  2352 , respectively, and so no clearance is present therebetween. For reference, enlarged views of the second enclosure housing  2302  and the actuator  2424  are depicted in  FIGS.  24 C- 24 F . Unless otherwise specified, description of the components of the second enclosure housing  2302  and second actuator  2424  may apply to the first enclosure housing  2301  and first actuator  2422 . 
     As shown in  FIGS.  24 C- 24 F , in certain embodiments, a medial surface  2461  of the inactive layer  2360  is coupled directly to the medial wall  2352 . Thus, the inactive layer  2360  forms a direct barrier between the medial wall  2352  and the active layer  2362 . In certain examples, the inactive layer  2360  is disk-shaped and extends along an entire lateral side  2453  of the medial wall  2352 , separating the medial wall from the lateral shell  2372  as shown in  FIG.  24 D . In certain examples, the inactive layer  2360  is beam- or strip-shaped and linearly extends along a diameter of the corresponding medial wall  2352 , intersecting the lateral shell  2372  at ends thereof. In still other examples, a disk- or beam-shaped inactive layer  2360  only extends along portions of lateral side  2453  of the medial walls  2352 , as shown in  FIGS.  24 E and  24 F . In such examples, the inactive layer  2360  may either form a partial separation between the medial wall  2352  and the lateral shell  2372  ( FIG.  24 E ), or no separation therebetween ( FIG.  24 F ). 
     In still other embodiments, the active layer  2362  of the actuator  2422  has a medial surface directly coupled to the medial wall  2352  (not shown), and the medial wall  2352  itself functions as an inactive layer for the actuator  2442 . Accordingly, the medial wall  2352  may be formed of a thin and flexible material layer such as polymer or silicone and is configured to be controllably deformed upon application of an electric field to the active layer  2362 . In some examples, the medial wall  2352  is formed of Ti or TiO 2  and has a thickness between about 0.02 mm and about 0.1 mm, such as about 0.025 mm, similar to the inactive layer  2360 . In such examples, the active layer  2362  may be formed of PZT, BaTiO 3 , SrTiO 3 , or other ferroelectric materials, and have dimensions similar as described above with reference to  FIGS.  23 A- 23 C . 
     In operation, the application of electrical signal to the active layers  2362  causes deformation thereof, thereby modulating the medial walls  2350 ,  2352  along which the active layers  2362  are disposed. Accordingly, the modulation of the medial walls  2350 ,  2352  modulates the positions of lateral shells  2370 ,  2372  and batteries  2328 ,  2328  coupled thereto relative to the tympanic membrane, thereby modulating the tympanic membrane which sends impulses to the user&#39;s brain via the ossicular chain and cochlea. By utilizing the first and second enclosure housings  2301  and  2302  as moving masses themselves, the hearing aid  2400  enables better utilization of total mass and reduces the movement of internal components thereof. Thus, the hearing aid  2400  may provide a more stable internal environment with reduced undesired micro-movement, while further improving mass utilization by modulating the enclosure housings  2301 ,  2302 . 
       FIG.  25    depicts a schematic cross-sectional view of an alternative compact hearing aid  2500 . The compact hearing aid  2500  includes a housing  2501  with an internal profile shaped to house and support a stack of components, including a microphone  2508 , a processor  2514 , a first portion  2526 , shown as a first battery, and a second portion  2528 , shown as a second battery, coupled to the first battery  2526  by a rigid connecting member  2520 . The compact hearing aid  2500  further includes an actuator  2522  coupled to a lateral side of the second battery  2528  opposite the connecting member  2520 , and a battery support  2536  disposed on a proximal side of the first battery  2526  that functions as a modulation guide and force to push against. The compact hearing aid  2500  is substantially similar to the hearing aids described above, but for the actuator  2522  being disposed on the lateral end of the second battery  2528  and coupled to an internal surface of a lateral end of the housing  2501 . 
     As discussed above, the compact hearing aid can be of any suitable size and shape with components of various size and shape; however, each configuration generally requires the same various components, for example, the microphone, energy source, actuator, and processor. 
     The actuator  2522  generally comprises a tubular or cylindrical stacked piezoelectric actuator with a mechanical amplifier. For example, as shown in  FIG.  25   , the actuator  2522  comprises a piezoelectric stack  2542  coupled to a mechanical amplifier  2540 . The piezoelectric stack  2542  may include any suitable number of layers (e.g., disks) formed of piezoelectric materials. For example, the piezoelectric stack  2542  may include between one and ten layers, such as between two and eight layers, such as five layers, formed of piezoelectric materials. In certain embodiments, one or more of layers of the piezoelectric stack  2542  are formed of PZT or similar ferroelectric materials, such as lead magnesium niobate-lead titanate (PMN-PT) and the like. Generally, the piezoelectric stack  2542  has a height H between about 0.5 mm and about 4 mm, such as between about 1 mm and about 2 mm. Each layer of the piezoelectric stack  2542  may have a diameter or width D between about 0.5 mm and about 2.5 mm, such as between about 0.5 mm and about 2 mm. 
     The mechanical amplifier  2540  may include any suitable type of displacement amplifier. For example, the mechanical amplifier  2540  may include a two-stage flexure-based displacement amplifier. The mechanical amplifier  2540  is configured to transform an input mechanical energy provided by the piezoelectric stack  2542  to an enlarged output mechanical energy for modulation of the second battery  2528  and thus, the first battery  2526  coupled thereto. Accordingly, the mechanical amplifier  2540  may transform a relatively small displacement of the piezoelectric stack  2542  to a desired larger displacement applied to the batteries  2526 ,  2528  for effective modulation thereof. In certain embodiments, the mechanical amplifier provides a displacement amplification between about 20× and about 100×, such as between about 25× and about 35×. 
     Factors considered in the design of the mechanical amplifier  2540  include the amount of force and displacement generated by the piezoelectric stack  2542 , and the amount of force to be applied to, and the amount of displacement of, the tympanic membrane to improve the user&#39;s hearing. The amount of force may vary based on the modulating mass or masses of between about 20 mg and about 30 mg, between about 0.05 microns and about 5.0 microns of displacement with a force of between about 0.001 Newtons (N) and about 0.05 N, across the audible frequency range. 
     Methods of Implantation 
     The disclosed compact hearing aids are implantable by any suitable implantation method.  FIG.  10    is a process flow of one such method  1000 . 
     Prior to the method  1000 , an optional cleaning may be performed to clean the tympanic membrane and the proximal external auditory canal. 
     The method  1000  generally includes identifying the optimal location for placement of the compact hearing aid at operation  1010 , anesthetizing the location for placement at operation  1020 , making an incision, or any other puncture, at the location for placement at operation  1030 , and inserting the compact hearing aid through the incision at operation  1040 . The method  1000  generally further includes confirming the placement and the functionality of the compact hearing aid at operation  1050 . 
     In one embodiment, the optimal location is the anterior inferior quadrant of the tympanic membrane. Accordingly, the method includes anesthetizing a portion of the anterior inferior quadrant, making a small incision, such as less than or equal to about 2 mm, for example less than or equal to about 1 mm, and inserting the compact hearing aid through the incision to position the compact hearing aid in the user&#39;s anterior inferior quadrant of the tympanic membrane. 
     As discussed above, some embodiments of the compact hearing aids include configurations that are adapted for easier insertion through the tympanic membrane. For example, at least one of the one or more flanges may include a slotted or interrupted flange, such as the compact hearing aid  700  shown in  FIG.  7   , to aid in placement across an incision in the tympanic membrane by rotating the compact hearing aid through the incision. 
     In another embodiment, such as the compact hearing aid  800  of  FIG.  8   , at least one of the one or more flanges, such as the medial flange, or the body of the compact hearing aid itself, is conically-shaped such that it serves as a dilator, which provides a profile to be pushed through the incision in the tympanic membrane to dilate the incision and allow the medial portion of the compact hearing aid to pass therethrough. 
     In yet another embodiment, at least one of the medial and laterial flange is a self-expanding flange that is insertable through the incision and expandable in the middle ear such that it will lie against the medial side of the tympanic membrane once expanded. In still further embodiments, the distance between the flanges, or intermittent portions thereof, is predetermined to allow for implantation and for providing adjustment for variable thickness of the tympanic membrane and/or variable force. 
     In even further embodiments, the compact hearing aid includes multiple pieces, which can be coupled together to form the entire compact hearing aid. In such embodiments, the medial and lateral flanges are generally connected by an array of connectors that are fixed in one or both halves and that couple to corresponding receptacles on one or both halves. After one piece of the compact hearing aid is inserted through the incision, for example through the tympanic membrane, then the second piece is coupled to the already inserted piece, for example, by piercing the tympanic membrane with the array of pins that mate with the already inserted piece. In still further embodiments, one piece is inserted through the incision to the medial side of the tympanic membrane and a second piece is coupled to the first piece across the tympanic membrane at a location a distance away from the initial placement incision. In such embodiments, the initial placement incision will heal up. 
     Methods of Removal for Emergency or Safety Reasons 
     The disclosed compact hearing aids can be quickly and safely removed for safety and emergency reasons. For example, as discussed above, embodiments of the compact hearing aids are configured to turn off upon recognition of a particular audio signature frequency. If the particular audio signature fails to turn off the compact hearing aid, or if the compact hearing aid needs to be removed for emergency reasons, then the device may be inactivated and/or removed by physical means. 
     In one embodiment, the lateral flange of the disclosed compact hearing aids includes a switch, a pressure switch, a contact point, a slide, or any combinations thereof. A medical professional may contact the switch, the pressure switch, the contact point, the slide, or the combinations thereof using basic medical tools in an emergency room or other medical setting to inactivate the compact hearing aid after the compact hearing aids fails to turn off in response to the audio signature frequency. In some embodiments, the lateral flange of the disclosed compact hearing aids incorporates a feature to assist in the removal of the compact hearing aid that can be grasped or connected with general medical tools such as tweezers, probes, and forceps. 
     In still further embodiments, users of the disclosed compact hearing aids are provided with a custom configured inactivation or retrieval tool that can be used by a medical professional to remove or inactivate the device in emergency situations. 
     Devices for Implantation and Retrieval 
     The disclosed compact hearing aids can be implanted into a patient&#39;s ear during a minimally-invasive, outpatient procedure. In one embodiment, the disclosed compact hearing aids are inserted using a scalpel, or any suitable cutting instrument, to create a small incision, or any other puncture, and a tool is used to hold the compact hearing aid and position the contact hearing aid through the tympanic membrane. In another embodiment, an implantation tool, which generally includes an elongate rod having a cutting tool on a distal end thereof, is inserted through the ear canal to the appropriate position on the tympanic membrane. The cutting tool positions the compact hearing aid at the location for placement using a distal alignment ring guide, advances a cutting instrument, such as a blade or a needle, of a predetermined, suitable size to create an incision at the location for placement, and then advances the compact hearing aid across the tympanic membrane to dispose the compact hearing aid therethrough. 
     The configuration of the device for implantation and retrieval may be varied to more easily insert specific configurations of the disclosed compact hearing aids. For example,  FIGS.  11 A- 11 B  depict the compact hearing aid  900  of  FIGS.  9 A- 9 C  with a portion of an exemplary implantation tool. As shown in  FIGS.  11 A- 11 B , the implantation tool  1100  includes a sheath  1102  and an advancement rod  1104 . In operation, the sheath surrounds the compact hearing aid  900  and keeps the plurality of first flange tabs  906  and the plurality of second flange tabs  908  in their non-expanded position such that they lie flat alongside the compact hearing aid  900 , as shown in  FIG.  11 A . 
     A portion of the sheath  1102  is generally inserted through the incision made in the tympanic membrane and once the sheath  1102  has been inserted through the tympanic membrane, then at least a portion of the sheath  1102  is withdrawn. The compact hearing aid  900  is thus disposed through the tympanic membrane, such that a first portion of the compact hearing aid  900  is disposed on the medial side of the tympanic membrane and a second portion of the compact hearing aid  900  is disposed on the lateral side of the tympanic membrane. Once the portion of the compact hearing aid  900  having the plurality of first flange tabs  906  is released from the sheath  1102 , the advancement rod  1104  maintains its position while the sheath  1102  is withdrawn. The first flange tabs  906  expand, flare out, or otherwise deploy, and form a flange alongside the tympanic membrane, as shown in  FIG.  11 B . 
     In another embodiment, one or more tools, such as cupped forceps, are inserted through a primary opening for accessing the medial side of tympanic membrane, thereupon the two or more components are joined across the tympanic membrane through various mechanisms, such as pins or snaps. The one or more tools, such as the cupped forceps are then removed. 
       FIGS.  15 A- 15 B  depict an alternative embodiment of an implantation tool  1500 . The implantation tool  1500  includes a distal cup  1501 , a proximal cup  1502 , a connecting member  1503 , an advancing member  1504 , a handle  1505  and an actuating trigger  1506 . The implantation tool  1500  is configured to hold one or more devices to be implanted. 
     The operation of the implantation tool  1500  will be described in the context of inserting a compact hearing aid through the tympanic membrane. However, it is contemplated that the implantation tool  1500  is useful to implant any suitable device in any suitable location throughout the body. 
     As shown in  FIG.  15 B , the implantation tool is configured to hold a first portion  1508  and a second portion  1510  of a compact hearing aid, such as the compact hearing aids disclosed herein. 
     In operation, the distal cup  1501  holding the first portion  1508  is advanced through an incision in the tympanic membrane such that the distal cup  1501  and the first portion  1508  are disposed on the medial side of the tympanic membrane while the proximal cup  1502  and the second portion  1510  are disposed on the lateral side of the tympanic membrane. The actuating trigger  1506  can then be used to actuate the distal cup  1501  and/or the proximal cup  1502  to snap the first portion  1508  and the second portion  1510  of the compact hearing aid together through the tympanic membrane at a distance away from the incision. Once the compact hearing aid has been snapped together and implanted through the tympanic membrane, the implantation tool  1500  is withdrawn through the incision and the hearing aid is left in place through the tympanic membrane. 
     Devices and Systems for Recharging 
     The present disclosure further contemplates recharger devices and systems for providing a user interface to recharge the implanted compact hearing aids easily. The recharger devices and systems interact with the charging circuitry to recharge the disclosed compact hearing aids. The recharger devices and systems are generally disposed in the ear canal, over the ear, around the ear, or in the vicinity of the user&#39;s head. Exemplary rechargers include ear buds, inner ear canal inserts, ear muffs, over-the-ear clips, glasses stem clips, devices in or around a pillow, and devices in or around the vicinity of the user&#39;s head, that can be placed in the ear canal, over the ear, around the ear, or in the vicinity of the user&#39;s head to interact with the recharging circuit. In some cases, the recharger device itself will need to be recharged. In one embodiment, the recharging system is a cradle system that provides a support cradle for the recharge device, which is coupled to a power source such as, an outlet, a USB port, or an automobile power source. In another embodiment, the recharge device itself may be directly connected to a power source through a connector, such as prongs. It is also contemplated that the recharging system can be modular such that a head set would provide holders for the ear components and hold them in place while they are being worn by the patient and additional holders for holding them while they are recharging. The charging components that are placed in the ear canal can be disconnected from the head set system to be more discreet and to allow for mobile recharging. 
     Docking Devices 
     The present disclosure also contemplates docking devices for docking one or more devices in a user&#39;s ear, such as through the tympanic membrane. Like embodiments of the compact hearing aids described herein, the docking devices may also include any suitable configurations of a first flange and a second flange connected by a connecting member. However, the docking devices generally do not include the components of the hearing aid described above. Instead, the docking devices generally include a hollow portion therethrough, which is predesigned to dock another device therein. Much like the disclosed compact hearing aids, the docking devices can be inserted during a minimally-invasive outpatient procedure. The procedure generally includes identifying the optimal location for placement of the docking device, anesthetizing the location for placement, making an incision, or any other puncture, at the location for placement, and inserting the docking device through the incision. The procedure may also include cleaning the location for placement, as well as confirming the placement and the functionality of the docking device after the docking device has been placed. 
     Suitable devices to be docked include, but are not limited to, biometric devices, diagnostic instruments, entertainment modules, covert communication modules, therapeutic devices, fitness tracking devices, health tracking devices, tissue stimulating devices, and assistive hearing devices. These docking devices beneficially provide a docking station in the ear, such as through the tympanic membrane, which allows for various devices to be placed therein over time. Since the docking device has already been placed at the predetermined location for placement, an additional incision does not need to be made at the placement location when the device is docked in the docking device. 
     Stimulating and/or Modulating Devices 
     While the present disclosure discusses the disclosed devices being used as compact hearing aids. The present disclosure also contemplates stimulating and/or modulating devices, which are positionable, for example, in any tissue throughout the user&#39;s body. Such tissue stimulating devices similarly include a housing with various components therein, such as one or more sensors, one or more masses, one or more energy sources, which may be used as the one or more masses, one or more processors, and one or more actuators. The one or more sensors are generally any suitable sensors to provide a predetermined output, the predetermined output being based on the desired effect on the user&#39;s body. Exemplary output includes, but is not limited to, mechanical, electrical, and thermal output. In operation, the stimulating and/or modulating devices are useful to effect change on a number of different tissues in the body, such as muscles, ligaments, membranes, bones, and cartilage. 
     CONCLUSION 
     Embodiments of the present disclosure provide improved compact hearing aids that use vibration transduction to directly or indirectly modulate the velocity or the position of the tympanic membrane. This direct or indirect modulation of the velocity or the position of the tympanic membrane significantly improves sound quality for the user. The disclosed compact hearing aids are more compact, more comfortable, and less cosmetically noticeable. Indeed, since the disclosed compact hearing aids may be disposed in the ear canal and across the tympanic membrane, the disclosed compact hearing aids are invisible from the outside observer. In addition, because of the compact design of the disclosed compact hearing aids, the compact hearing aids do not totally block the ear canal. Instead, the disclosed compact hearing aids leave the ear canal unobstructed and thus provide a more natural and improved sound quality for the user. Additionally, the disclosed compact hearing aids provide additional functionality, such as avoiding the canal occlusion effect and hearing aid feedback associated with conventional hearing aids. Moreover, the disclosed compact hearing aids can be inserted and removed during a minimally-invasive outpatient procedure. 
     While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.