Abstract:
The present invention provides an apparatus and method for inserting a relatively compact hearing aid at least partially through the tympanic membrane using a simplified surgical procedure. The hearing aid includes a microphone, an amplifier, and at least one speaker that can be assembled into a single enclosure for insertion through the tympanic membrane. The simplified surgical procedure can be performed on an outpatient basis and generally includes anesthetizing a portion of the tympanic membrane, forming an incision with a cutting instrument in the tympanic membrane and inserting the hearing aid at least partially therethrough. Incisions and placement of a tube in an tympanic membrane for car drainage is routinely performed in pediatric patients and combines low morbidity and good patient tolerability. The tympanic membrane restrains the hearing aid in position for at least a period of time. A power source, such as a battery, powers the hearing aid. Further, a receiver may be included with the hearing aid and can control the hearing aid from external sources. The receiver can control the amplified volume, receive sound transmissions from the opposite ear or a hearing aid in the opposite ear or receive personal communications.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to assistive hearing devices. More specifically, the present invention relates to a hearing aid mounted internally to an ear. 
     2. Background of the Related Art 
     Hearing devices 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. Common 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 aides relatively bulky and objectionable for cosmetic reasons. 
     An alternative to externally mounted hearing aides are internally mounted hearing aids disposed in an ear canal of a user. Such internally mounted hearing aides 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 that impact the tympanic membrane. 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 visible in the ear canal by peering at the head of the user from the side. 
     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 transmits the sound impulses without reconverting to audio sound waves from a speaker. A separate magnet can be 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. Typically, however, the remainder of the hearing aid is inserted into the ear canal or on the outer ear and can cause to 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 cutting through the tympanic membrane, microscopically drilling bone structure and screwing the magnet to the malleus of the ossicular chain in the middle ear. Such procedures are expensive and can be painful. 
     Therefore, there remains a need for a relatively compact hearing aid that can be inserted in the ear canal and/or through the tympanic membrane using simplified surgical procedures and that can be hidden from external view. 
     SUMMARY OF THE INVENTION 
     The present invention provides an apparatus and method for inserting a relatively compact hearing aid at least partially through the tympanic membrane using a simplified surgical procedure. The hearing aid includes a microphone, an amplifier, and at least one speaker that can be assembled into a single enclosure for insertion through the tympanic membrane. The simplified surgical procedure can be performed on an outpatient basis and generally includes anesthetizing a portion of the tympanic membrane, forming an incision with a cutting instrument in the tympanic membrane and inserting the hearing aid at least partially therethrough. Incisions and placement of a tube in an tympanic membrane for ear drainage is routinely performed in pediatric patients and combines low morbidity and good patient tolerability. The tympanic membrane restrains the hearing aid in position for at least a period of time. A power source, such as a battery, powers the hearing aid. Further, a receiver may be included with the hearing aid and can control the hearing aid from external sources. The receiver can control the amplified volume, receive sound transmissions from the opposite ear or a hearing aid in the opposite ear or receive personal communications. 
     In one aspect, the invention provides an apparatus for enhancing hearing, comprising a microphone, an amplifier coupled to the microphone, a speaker coupled to the amplifier, the microphone, the amplifier and the speaker being connected to each other and insertable at least partially through a tympanic membrane of a user. In another aspect, the invention provides a method of inserting a hearing aid into an ear comprising inserting a cutting device into an ear, forming an incision in a tympanic membrane, and inserting a hearing aid comprising a microphone, an amplifier and a speaker at least partially through the tympanic membrane. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     So that the manner in which the above recited features, advantages and objects of the present invention are attained and can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the embodiments thereof which are illustrated in the appended drawings. 
     It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments. 
     FIG. 1 is a cross-sectional schematic of an car having the hearing aid inserted through the tympanic membrane. 
     FIG. 2 is a schematic perspective view of the hearing aid. 
     FIG. 3 is a schematic perspective view of an alternative embodiment of the hearing aid. 
     FIG. 4 is a schematic perspective view of an alternative embodiment of the hearing aid. 
     FIG. 5 is a schematic cross sectional view of an alternative embodiment of the hearing aid. 
     FIG. 6 is a schematic cross sectional view of an alternative embodiment of the hearing aid. 
     FIG. 7 is a schematic end view of the embodiment shown in FIG.  6 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 is a cross-sectional schematic view of a hearing aid inserted through the tympanic membrane in an ear of a user. The ear includes an outer ear  10 , an ear canal  12  coupled to the outer ear  10 , a tympanic membrane  14  disposed near a distal end of the ear canal  12  from the outer ear  10 . An ossicular chain  15 , located in a middle ear and disposed on an opposite side of the tympanic membrane  14  from the outer ear  10 , couples and amplifies vibrations from the tympanic membrane  14  to an inner ear having a spiral structure known as the cochlea  20 . The cochlea  20  converts the vibrations into impulses to the brain. The structure of the outer ear  10  provides a “funnel” to direct and amplify sound waves into the ear canal  12 . 
     The hearing aid  22  of the present invention can be inserted through the outer ear  10  into the ear canal  12  and at least partially through the tympanic membrane  14 . The hearing aid  22  includes a microphone, an amplifier coupled to the microphone and at least one speaker, described in more detail below. The hearing aid  22  receives sound waves conducted from the outer ear  10  through the ear canal  12 , converts the sound waves into electrical or electromagnetic signals, amplifies the signals and converts the amplified signals into amplified sound waves. The amplified sound waves impact the tympanic membrane  14 , and/or portions of the middle and inner ear, and vibrate the ossicular chain  15 , specifically the malleus  18 , the incus  16  and the stapes  17 . These three bones in the ossicular chain  15  act as a set of levers that amplify the vibrations received by the tympanic membrane  14 . The stapes  17  is coupled to the entrance of a spiral structure known as the cochlea  20  that contains an inner ear fluid. The mechanical vibrations of stapes  17  causes the fluid to develop fluid impulses that causes small hair-like cells (not shown) in the cochlea  20  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 perspective view of the hearing aid  22 . The hearing aid includes a microphone  24 , an amplifier  26  coupled to the microphone, at least one speaker  28  coupled to the amplifier and a power source  32 , such as a battery. The materials that contact the tissues of the ear are preferably biocompatible, such as silicon, titanium, fluoroplastics or other materials. The microphone  24  converts the sound waves or acoustic energy into electrical or electromagnetic signals. The amplifier  26  amplifies the signals from the microphone to enhance the hearing and hence provide increased hearing capabilities. The speaker  28  reconverts the amplified signals into amplified sound waves and emits the sound waves to the ear. The microphone, amplifier and speaker can be inserted within a tube  33  to form a unitized assembly. Alternatively, the microphone, amplifier and/or speaker can be attached together to form the unitized assembly with adhesives, such as epoxy, or with mating threads or by soldering or welding or other known attachment methods. Alternatively, the microphone, amplifier and speaker may be housed independently and/or move independently of each other to reduce sound alteration or attenuation. 
     The hearing aid  22  may also include the flanges  34  and  36  disposed along the tube  33 . The flanges assist in retaining the hearing aid  22  in the tympanic membrane  14 . Typically, the microphone  24  would be placed on the end of the hearing aid  22  facing the outer ear canal  12 . The microphone  24  can be located on a flange in the assembly of the hearing aid  22 . Similarly, the speaker  28  can be located on a flange in the assembly. The hearing aid  22  can also include a vent hole or vent holes  30  of varying sizes and configurations formed therethrough. The vent hole  30  assists in equalizing pressures between an ear region on each side of the tympanic membrane  14 . Other embodiments may not include such vent hole(s). Alternatively, one or both of the flanges can comprise the power source, such as a battery, connected to the other components of the hearing aid  22 . 
     The microphone  24  can be a high sensitivity microphone  24 . Preferably, the amplifier  26  can be a high efficiency, high gain amplifier that can amplify the sounds preferably by at least 25 dB and more preferably by at least about 45 dB. The amplifier can be assisted by the natural amplification of the external ear  10  and the ear canal  12 . A filter (not shown) can be used to filter noise and can include analog-to-digital and digital-to-analog converters. For example, analog signals from the microphone could be converted to digital signals, where digital signals are less sensitive to noise interference from extraneous transmission sources, such as mobile radio equipment, automobile telephones, and other electromagnetic waves. The digital signals could then be amplified, and the digital signals reconverted to analog signals for output through the speaker. 
     The hearing aid  22  preferably produces frequency distortions having levels no greater than about 1% at 500 Hz, 1% at 800 Hz and 0% at 1600 Hz and is preferably able to reproduce sounds from about 20 Hz to about 20 kHz. It is believed that the speaker will reduce the inherent attenuation of sound transmitted across air to the tympanic membrane that can occur in other hearing aids, because the speaker is in contact with the membrane itself. The power source  32  may advantageously be a battery, such as a nickel-cadmium or lithium cell type battery. Preferably, the power source  32  would last at least as long as the hearing aid  22  remains inserted through the tympanic membrane  14 , typically one to two years. Alternatively, the power source  32  can be a remote power source that supplies energy to the other components of the hearing aid  22  through electromagnetic radiation, such as infrared radiation waves or ultrasonic waves. In such example, the hearing aid  22  could include a remote transmitter (not shown) to transmit the energy and a receiver (not shown) attached to the hearing aid  22  to receive and convert the energy into electrical power for the components. The brands and models for the components described herein are illustrative only. Other brands and/or models may also be used. 
     FIG. 3 is a schematic perspective view of an alternative embodiment of the hearing aid. Similar elements of the embodiments shown in FIGS. 2 and 3 are similarly numbered. The embodiment of FIG. 3 shows a plurality of speakers  28   a-c.  Preferably, the hearing aid  22  is partially inserted through the tympanic membrane  14 , shown in FIG.  1 . With such a placement, speaker  28   a  would be disposed outwardly toward the ear canal  12 . Speaker  28   c  would be disposed inward of the ear canal on the inside of the tympanic membrane  14  and toward the ossicular chain  15  of the middle ear. It is believed that the speaker  28   c  may provide additional impulses in the middle ear and toward the cochlea  20  through a window in the cochlea. A middle speaker  28   b  can be disposed between speakers  28   a  and  28   c  for additional sound output on either side of the tympanic membrane, depending on the intersection of the hearing aid  22  with the tympanic membrane  14 . 
     The hearing aid  22  may also include a receiver  38 . The receiver  38  may be a frequency modulation (FM), amplitude modulation (AM) receiver, ultrasound receiver or other types of receivers and can have several functions. First, the receiver can be used to remotely control the components of the hearing aid  22 , such as the amplifier  26 . A remote transmitter can provide output signals to be received by the receiver  38  and adjust, for example, the amplification to avoid under or over-amplification of the converted audio signal from the microphone  24 . Additionally, the receiver can be used to receive transmissions from an opposite ear or from a hearing aid device in the opposite ear. The receiver can also be used to receive personal communications transmitted to the user. For instance, radio broadcasts, personal voice massaging, and other custom input can be transmitted to the receiver  38  to be amplified and then output through the speakers  28   a-c.    
     FIG. 4 is a schematic perspective view of an alternative embodiment of the hearing aid. Similar elements of the embodiments shown in FIGS. 2,  3  and  4  are similarly numbered. The hearing aid can be powered from a remote power source that supplies energy to the amplifier and other components of the hearing aid  22  through electromagnetic radiation, such as infrared waves. In such example, the hearing aid  22  would include a remote transmitter  37  to transmit the energy and a receiver  39  coupled to the hearing aid  22  to receive the energy and convert the energy into electrical power for the various components. 
     FIG. 5 is a schematic cross sectional view of an alternative embodiment of the hearing aid. Similar elements of the embodiments as shown in FIGS. 2,  3 ,  4  and  5  are similarly numbered. The hearing aid  22  can be assembled into a unit  23  that resists vibrational effects resulting from the movement of the tympanic membrane on at least one member of the components including the microphone  24 , amplifier  26  and speaker  28 . It is believed that such an arrangement may reduce sound distortion or attenuation caused by the relative movement of the components with the tympanic membrane to which the hearing aid is coupled, similar to the well known Doppler effect that causes an apparent change in the frequency of waves from relative motion between a sound source and a sound receiver. FIG. 5 provides one exemplary embodiment of a vibration dampening unit. 
     A flange  34  is coupled to a chamber  40  that houses a microphone  24 . The chamber  40  is coupled to a chamber  42  that houses a speaker  28 . The chamber  42  is coupled to a chamber  44  that houses an amplifier  26 . The chamber  44  is coupled to a power source  32 , such as a battery. The microphone  24  is electrically coupled to the amplifier  26  and the amplifier  26  is electrically coupled to the speaker  28  and to the power source  32 . One or more sound transmissive windows  48 ,  50  are coupled to the chamber  42  and allow the sound waves from the speaker  28  to be transmitted through the chamber  42  to the tympanic membrane, shown in FIG.  1 . One or more of the chambers  40 ,  42  and  44  can be at least partially filled with a fluid. It is believed that the mass of the fluid and the resulting inertia of the components within the fluid can reduce the motion of the components relative to incoming sound waves to the microphone and/or outgoing sound waves from the speaker. Other vibration dampening effects are possible, such as use of elastic compounds instead of fluids, air suspension, gyroscopic inertia forces on components produced by rotating the components rapidly, and the other methods known to those in the art. 
     FIG. 6 is a schematic partial cross sectional view of another embodiment of the hearing aid. The hearing aid  22  includes elements previously described in reference to FIGS. 2-5 and further includes a chamber  52  for vibrational dampening, similar to the vibrational dampening aspects described in reference to FIG. 5. A flange  35  is coupled to a microphone  24 . An outer shell  54  is disposed around the microphone  24 , forming a chamber  52  that contains a fluid therebetween. The outer shell  54  is coupled to a flange  34 . The flange  34  is flexibly coupled to the flange  35  by a flexible coupling  56  that is used to retain the fluid within the chamber  52 . One or more openings  58  formed in the flange  35  allow sound waves to be received by the microphone  24 . The outer shell  54  is coupled to an amplifier  26  disposed either within the outer shell or adjacent the outer shell. A power source  32 , such as a battery, is coupled to the amplifier  26 . The amplifier  26  is coupled to one or more speakers  28   a-b.  The speakers  28   a-b  can be disposed on the outer shell  54 . Alternatively, the speakers can be disposed within the outer shell and can transmit sound through an acoustically transparent medium, such as shown in FIG. 5, to the outside of the shell. 
     FIG. 7 is a schematic end view of the embodiment shown in FIG. 6. A flange  35  is coupled to a flange  34 . The flange  34  is coupled to an outer shell  54 . The outer shell preferably supports speakers  28   a-b.  A microphone  24  is disposed radially inward of the outer shell  54  in a chamber  52 . Preferably, the flange  35  has one or more openings  58  through which sound waves may be received by the microphone  24 . 
     Referring to FIG. 1, the hearing aid  22  can be inserted at least partially through the tympanic membrane  14  with a relatively unobtrusive surgical procedure. One exemplary procedure would include anesthetizing a portion of the membrane by inserting a drop of phenol or other fluids on the tympanic membrane  14 . Alternatively, the tympanic membrane  14  can be anesthetized by injecting a localized anesthetic, such as lidocaine, into the tissues of the ear canal  12 . A tubular instrument (not shown) is inserted into the ear canal  12 , such as an ear speculum, to view the tympanic membrane and to provide a safe conduit for a cutting instrument. In conjunction with an operating microscope, the cutting instrument is inserted through the ear speculum and forms a small slit  25  in the tympanic membrane  14 . The cutting instrument may be a knife, a laser, an ultrasonic transducer, and other cutting devices. The small incision can be done in a physician&#39;s office or on an out-patient basis with generally minimal difficulty. After the slit  24  is formed in the tympanic membrane  14 , the hearing aid  22  is inserted through the ear canal  12  and at least partially through the slit  24 . Preferably, the hearing aid  22  is inserted through the tympanic membrane  14  so that a portion of the hearing aid extends into the ear canal  12 . The tympanic membrane  14  restrains the hearing aid  22  from becoming dislodged into the ear canal  12 . A portion of the hearing aid  22  that extends into the ear canal  12  provides a surface through which the microphone  24 , shown in FIGS. 2-7, can receive input of sound waves through the ear canal  12 . Typically, the tympanic membrane will grow and heal around the hearing aid  22 . In an extended period of time, such as one to two years, the tympanic membrane  14  may press the hearing aid  22  out of the membrane. Further, the hearing aid  22  may be secured to the tympanic membrane  14 , to a ring on the tympanic membrane (not shown), known as a tympanic membrane annulus, or to the ear canal  12 . Due to the relatively noninvasive and simplified procedure, the hearing aid  22  can be discarded and a new hearing aid inserted in much the same manner with a new battery to last for the next period of time in which the hearing aid  22  remains secured in the tympanic membrane  14 . Alternatively, the same hearing may be re-inserted easily in the office with a new battery or power source. 
     While foregoing is directed to the preferred embodiment of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow. For instance, the receivers can be combined into the various embodiments. The vibration dampening aspects described can be applied to any or all of the components. Further, the sequence of assembly can be varied, for example, by placing the speaker and receiver adjacent each other and the amplifier adjacent a power source. Thus, it is understood that the various components that coupled to each other can be connected indirectly or directly to each other.