Output transducers for hearing systems

Apparatus for directly stimulating a tympanic membrane or other acoustic member comprising a support with a plurality of activatable elements. The support can be mounted on the tympanic membrane and the activatable elements are distributed on the support to provide a distributed vibration to the tympanic membrane.

CROSS-REFERENCES TO RELATED APPLICATIONS

The present application is related to commonly owned U.S. patent application Ser. No. 10/902,660, filed Jul. 28, 2004, entitled “Transducer for Electromagnetic Hearing Devices”Ser. No. 11/121,517, filed May 3, 2005, entitled “Hearing System Having Improved High Frequency Response,” and Ser No. 11/248,459, filed on Oct. 11, 2005, entitled “Systems and Methods for Photo-Mechanical Hearing Transduction,” the complete disclosures of which are incorporated herein by reference. The present application is also related to commonly owned U.S. Pat. Nos. 6,084,975, 5,804,109, 5,425,104, 5,276,910 and 5,259,032 the complete disclosures of which are also incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates generally to hearing systems, output transducers, methods, and kits. More particularly, the present invention is directed to hearing systems that comprise a plurality of activatable elements that are distributed on a support component to produce vibrations, that correspond to the ambient sound signals, on a portion of the human ear. The systems may be used to enhance the hearing process of those that have normal or impaired hearing.

Many attempts have been made to magnetically drive the eardrum and/or middle ear ossicles. To date, three types of approaches have been used. The first approach was to attach a permanent magnet, or a plurality of magnets, to one of the ossicles of the middle ear. A second approach was to attach super-paramagnetic particles to the outer surface of the ossicles using a collagen binder. The third approached suspended permanent magnets on the eardrum with a flexible support that clings to the eardrum through the use of a fluid and surface tension. The last approach is referred to herein as the “ear lens system,” and is described in commonly owned U.S. Pat. Nos. 5,259,032, 6,084,975 both to Perkins et al., the complete disclosures of which were previously incorporated herein by reference.

As shown inFIGS. 3A and 3B, in the conventional ear lens system, an output transducer assembly26comprises a magnetic frustum28that is embedded on a support component14that floats on a surface of the tympanic membrane16. An input transducer (not shown) delivers a signal to the output transducer assembly26to cause a vibration in the tympanic membrane16that corresponds to the ambient sound received by the input transducer assembly.

While the ear lens system has been successful, the ear lens system can still be improved. For example, an alignment of the magnetic axis of the magnet with the applied magnetic field lines is important for the proper operation of the ear lens system. If the magnet is not properly aligned with the external field lines, it will not vibrate in a way that leads to the best transmission of sound into the ear. Thus, if the magnet is not properly aligned, the magnet may simply rotate rather than experience translational motion. Unfortunately, the alignment problem is made very difficult by the tortuous and irregularly shaped human ear canal anatomy. In addition, it varies greatly from person to person. Therefore, if one attempts to generate a magnetic field using a device located in the ear canal, it is often very difficult to align the generated magnetic field with the magnetic axis of the permanent magnet on the ear lens system. Moreover, the current needed to generate a magnetic field to drive the ear lens with both sufficient force to enable hearing assistance and still have the battery last a reasonable amount of time for a product is on the boundary of current battery technology capabilities. This leads to the need to precisely control the spacing of the transmitter generating the driving magnetic field and the ear lens magnet.

The inefficiency of magnets floating on the tympanic membrane was reported in seven subjects, by Perkins (1996). The average maximum gain of 25 dB was at 2 kHz. However, above 2 kHz the gain decreased and was more variable. The reduced gain at high frequencies is a primary cause for abandoning the previous approach.

Furthermore, it has been known that that the tympanic membrane has multiple modes of vibrations above 1-2 kHz (Tonndorf and Khanna 1970). It is now known that this results in motions of the umbo, at the center of the tympanic membrane, in the three dimensions of space (Decraemer et al. 1994). These modes of vibrations were not initially considered in the design of the electromagnetic systems described by Perkins et al. Part of the reason for the inefficiency has to do with rotational motion of the magnet (instead of translational movement) which is inefficiently coupled to the tympanic membrane.

Measurements by Decraemer et al. (1989) and subsequent model calculations (Fay 2001; Fay et al. 2002) suggest that at frequencies above 1-2 kHz, the motion of the tympanic membrane is significantly higher, by up to 20 dB, at the outer edge than at the center of the tympanic membrane. This suggests that an outer portion of the tympanic membrane can be actuated more efficiently. Several experiments showed that indeed a small magnet attached near the peripheral edge moved quite a bit. However, this motion is reduced by as much as 20 dB at the umbo and is thus not well coupled to the center of the drum due the higher impedance there. In addition, the umbo motion is smoothly varying and does not have the wild amplitude fluctuations present at the outer edge of the eardrum.

Consequently, what are needed are hearing systems, output transducers and methods that can actuate the center of the tympanic membrane and a periphery of the tympanic membrane differently, so as to better reflect the natural movement of the tympanic membrane.

DESCRIPTION OF THE BACKGROUND ART

BRIEF SUMMARY OF THE INVENTION

The present invention provides hearing systems, output transducer assemblies and methods that improve actuation of an acoustic member of a subject. The output assemblies and hearing systems of the present invention may comprise a plurality of distributed, activatable elements so as to provide improved actuation of an acoustic member of a subject, and hence improved hearing.

The hearing systems and output transducers of the present invention are attached to an acoustic member of the middle or inner ear of the subject, and typically coupled to a tympanic membrane of the subject. It should be appreciated however, that the output transducers of the present invention may be removably or permanently attached to other acoustic members in the middle or inner ear. For example, the output transducer may be coupled to ossicular chain, cochlea, or the like. Thus, while the remaining discussion focuses on coupling of the output transducer to the tympanic membrane, the concepts of the present invention may be relevant to actuation other portions of the subject's inner or middle ear.

The hearing systems and output transducer assemblies typically include a support component that is configured to be coupled to an acoustic member of a subject and a plurality of activatable elements that are distributed over the support component. The activatable elements are configured to receive a signal from an input transducer and provide a distributed vibration across the acoustic member in accordance with the signal from the input transducer.

Multiple activatable elements (e.g., magnets), with a distributed weight equal to the weight of a single combined (lumped) element at the center, such that the weight of each element is inversely proportional to the number of elements, could be attached around the tympanic membrane annulus to obtain the same displacement as the single lumped element at the center of the tympanic membrane. In such embodiments, the activatable elements are distributed around the peripheral edge of the tympanic membrane and will be better able to vibrate the tympanic membrane particularly at high frequencies. However, when three or four small magnets are attached to the tympanic membrane there can be interaction between the magnets, with the net result being, that the magnets can detach, flip and bunch up together. To overcome this problem, the multiple magnets are preferably sized and spaced from each other so as to not interact with each other for a given platform material. Second, it is desirable to limit the actuation of a center portion of the tympanic membrane along a translation direction so that there is little transmission loss on the eardrum.

By distributing the activatable particles over a surface of a support component that is in contact with the tympanic membrane, a much larger activatable surface is generated. By intersecting more field lines, the distributed approach should be able to provide a much larger driving force to the tympanic membrane for the same amount of input current that is used in conventional lumped magnet output transducer assemblies. Thus, if the same amount of force is needed, it would be possible to reduce the amount of current while still providing the same amount of driving force. This in turn, will relax the placement tolerances of the transmitter relative to the output transducer assembly and may extend the battery life of the hearing system.

The plurality of activatable elements may be comprised of a variety of different types of elements. The type of activatable element will depend on the makeup of the rest of the hearing system. For example, if the input transducer assembly that receives the ambient sound produces an electromagnetic signal, the output transducer will comprise a plurality of electromagnetic elements. Likewise, if the input transducer produces an optical signal, the output transducer will comprise a plurality of photosensitive materials. Other suitable input transducer assembly include, but are not limited to, ultrasound, infrared, and radio frequencies. Consequently, a variety of different activatable materials, or the like, may be used for the activatable elements of the output transducer, depending on the type of input transducer assembly used in the hearing system.

One preferred embodiment of the activatable elements is an electromagnetic element, such as a magnetized ferromagnetic material (e.g., iron, nickel, cobalt, or the like). The magnetic material activatable elements are subjected to displacement by an electromagnetic field to impart vibrational motion to the portion of the acoustic member, to which it is attached, thus producing sound perception by the wearer of such an electromagnetically driven system.

In some embodiments, the output transducer assembly and hearing systems encompassed by the present invention may optionally have different sized, shaped elements, or different concentrations in a coating of the same activatable elements that are tuned in frequency to their respective quadrants of the tympanic membrane so as to provide direct drive actuation of the middle ear.

While the remaining discussion will focus on the use of an electromagnetic input and an electromagnetic output transducer assembly, it should be appreciated that the present invention is not limited to such transmitter assemblies, and various other types of transmitter assemblies may be used with the present invention. For example, the photo-mechanical hearing transduction assembly described in co-pending and commonly owned, U.S. patent application Ser. No. 11/248,459, filed Oct. 11, 2005, entitled “Systems and Methods for Photo-mechanical Hearing Transduction,” the complete disclosure of which is incorporated herein by reference, may be used with the hearing systems of the present invention. Furthermore, other transmitter assemblies, such as optical transmitters, ultrasound transmitters, infrared transmitters, acoustical transmitters, or fluid pressure transmitters, or the like may take advantage of the principles of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1shows a simplified cross sectional view of an outer ear10, middle ear12and a portion of an inner ear14. The outer ear10comprises a pinna15and an auditory ear canal17. The middle ear12is bounded by the tympanic membrane (ear drum)16on one side, and contains a series of three tiny interconnected bones: the malleus (hammer)18; the incus (anvil)20; and the stapes (stirrup)22. Collectively, these three bones are known as the ossicles or the ossicular chain. The malleus18is attached to the tympanic membrane16while the stapes22, the last bone in the ossicular chain, is coupled to a spiral structure known as a cochlea24of the inner ear14.

In normal hearing, sound waves that travel via the outer ear or auditory ear canal17strike the tympanic membrane16and cause it to vibrate. The malleus18, being connected to the tympanic membrane16, is thus also set into motion, along with the incus20and the stapes22. These three bones in the ossicular chain act as a set of impedance matching levers of the tiny mechanical vibrations received by the tympanic membrane. The tympanic membrane16and the bones may act as a transmission line system to maximize the bandwidth of the hearing apparatus (Puria and Allen, 1998). The stapes22vibrates in turn causing fluid pressure in the vestibule of the cochlea24(Puria et al. 1997).

The fluid pressure results in a traveling wave along the longitudinal axis of the basilar membrane (not shown). The organ of Corti sits atop the basilar membrane which contains the sensory epithelium comprising of one row of inner hair cells and three rows of outer hair cells. The inner-hair cells (not shown) in the cochlea are stimulated by the movement of the basilar membrane. There, hydraulic pressure displaces the inner ear fluid and mechanical energy in the hair cells is transformed into electrical impulses, which are transmitted to neural pathways and the hearing center of the brain (temporal lobe), resulting in the perception of sound. The outer hair cells are believed to amplify and compress the input to the inner hair cells. When there is sensory-neural hearing loss, the outer hair cells are typically damaged, thus reducing the input to the inner hair cells which results in a reduction in the perception of sound. Amplification by a hearing system may fully or partially restore the otherwise normal amplification and compression provided by the outer hair cells.

As shown inFIG. 2, one presently preferred coupling point of an output transducer assembly26of the present invention is on an outer surface of the tympanic membrane16.FIGS. 3A and 3Billustrate the output transducer assembly26ofFIG. 2in more detail. In the illustrated embodiment, the output transducer assembly26comprises an output transducer assembly26that is placed in contact with an exterior surface of the tympanic membrane16. The output transducer assembly26generally comprises a single high-energy permanent magnet28. A preferred method of positioning the output transducer assembly26is to employ a contact transducer assembly that includes magnet28and a support component30. Support component30is attached to, or floating on, a portion of the tympanic membrane16. The support component is vibrationally coupled to the tympanic membrane16and is typically comprised of a biocompatible material and has a surface area sufficient to support the magnet28. The peripheral edge of the tympanic membrane is attached to bone at the tympanic annulus15. The malleus18is partially visible through the semi-transparent tympanic membrane16. The inferior portion of the malleus, shown inFIG. 3Aby the dashed line, is also visible through the support element.

Preferably, the surface of support component30that is attached to the tympanic membrane substantially conforms to the shape of the corresponding surface of the tympanic membrane16, particularly the umbo area32. In one embodiment, the support component30is a conically shaped film that partially or fully encapsulates magnet28therein. In one configuration, support component comprises a transparent silastic support. In such embodiments, the film is releasably contacted with a surface of the tympanic membrane16. Alternatively, a surface wetting agent, such as mineral oil (not shown), may be used to enhance the ability of support component30to form a weak but sufficient attachment to the tympanic membrane16through surface adhesion. A more detailed discussion of a contact output transducer assembly is described in U.S. Pat. No. 5,259,032, the complete disclosure of which is incorporated herein by reference.

Applicants have performed modeling work on eardrum mechanics and have hypothesized and shown that the reason why the motion at the umbo32of the tympanic membrane16, and consequently the input to the cochlea, is smoothly varying is that the tympanic membrane16is deliberately mistuned (See Fay 2001; Fay et al. 2002). Thus, the design of the output transducer assembly26of the present invention lends itself to having the resonances localized to a particular quadrant or portion of the tympanic membrane16for a given input stimulus frequency. High amplitude motions at an outer edge of the tympanic membrane are indicative of resonance. For example, tones in the lower octaves of the audible frequency range may have preferred resonance on the posterior quadrant of the tympanic membrane, while the tones in upper octave range may have preferred resonance on the inferior quadrant, and mid frequency tones may have resonance in the anterior quadrant. These results suggest actuation of the eardrum in a likewise manner. The output transducer assemblies and hearing systems of the present invention may be used to provide selective drive actuation of different portions of the tympanic membrane.

FIGS. 4A to 6Dillustrate various examples of output transducer assemblies26that provides improved vibrations of the middle ear, particularly at frequencies in the 2 to 15 kHz range. In the illustrated embodiments, instead of placing a single, high-energy permanent magnet28at a center of the support component30, activatable material34(e.g., magnetic material) is distributed on a portion or all of the substrate that makes up support component30. The distribution of the activatable material34may be distributed uniformly or non-uniformly on one or more surfaces of or embedded within the support component30. Thus, certain parts of the ear lens can have a higher density of activatable material34than other parts. In addition, the activatable material34can be mixed directly into the substrate and then cured into the shape of the output transducer assembly26or the activatable material34could be attached later as a coating or printing on one or more surfaces of the support component30.

In embodiments where the activatable material is a magnetic material, some care must be taken to mix in the correct amount of magnetic material for a given particle size. If too much material is mixed into the substrate that forms the support component30, the entire structure will collapse on itself when the magnetic material is poled. In addition, as magnetic material is added to the substrate, it becomes much heavier, which adds to the insertion loss of the hearing system, which is acceptable if the effective force increases proportionately.

The distributed magnetic material over the support component has a number of advantages of a single, lumped permanent magnet. First, the magnetic force generated by the distributed magnetic particles will induce pressure over the entire surface of the tympanic membrane16, so as to be similar to acoustic pressure generated by the actual sound waves. Second, the distribution pattern of magnetic material over the surface of the tympanic membrane16may be changed or personalized to the individual subject so as to “tune” the response for each quadrant of the tympanic membrane.

FIGS. 4A-4Cillustrate one embodiment of a distributed output transducer assembly26of the present invention in which the activatable elements34are distributed and embedded within the support component30. In the illustrated embodiment, the activatable material is in the form of magnetic elements or particles. WhileFIG. 4Cillustrates that the magnetic elements are different sizes, the magnetic elements may be the same size or different sizes. Several different magnetic element sizes are envisioned for manufacturing the distributed magnet output transducer. For example, some preferred materials include, but is not limited to, a cobalt compound with samarium Sa2CO7(http://www.sigma-aldrich.com, product no. 339229) that have an estimated particle size that varies from about 20 μm to about 200 μm. Of course, if desired the magnetic elements may be smaller or larger

As shown inFIG. 4C, the magnetic elements34are spaced from each other so as to reduce and preferably prevent the magnetic interaction with each other. Moreover, the magnetic elements34may have a random distribution on or in the support component30over the tympanic membrane. However, even with such a random distribution, as shown by the “N” and “S” orientation in each of the magnetic elements34, it is desirable to have a magnetic orientation of each magnet be aligned in the same direction as the other magnetic particles. WhileFIG. 4Cshows the “S” pole being directed toward the tympanic membrane16, it should be appreciated that any orientation of the magnetic elements may be possible, as long as each of the magnetic elements34are substantially aligned with each other.

If the magnetic poles of the magnetic particles aren't substantially aligned in the same direction as each other, there may not be a net magnetic force in the far field. The alignment of the poles of the magnetic particles34is typically achieved during a magnetization period during manufacturing. Initially the ferromagnetic domains are not magnetized. In ferromagnetic materials, application of a magnetic field causes the ferromagnetic elements to be temporarily magnetized. If the field strength is sufficiently high, the ferromagnetic substance becomes a permanent magnet. When a magnetic field is applied to a magnet or a plurality of magnets—such as the present invention, each of the magnets experience a magnetic moment due to the dipole nature of the magnets. The moment is such that it exerts a force on all of the dipoles, which results in an alignment of the magnetic elements with the applied magnetic field. If the compliance of the support component30is such that the magnetic moment overcomes the local restoring force of the support component30, the magnetic elements will tend to be substantially aligned with the uniform magnetic field. Once aligned, local mechanical forces due to, for example gravity and electrostatic charges, may tend to restore the particles back into a somewhat random orientation in the compliant substrate. However, to minimize this, the substrate that forms the support component can be cured rapidly to decrease the compliance and thus preserve the poled orientation of the embedded magnetic elements34. It is contemplated that an external static magnetic field can be applied in the poled direction such the magnetized domains stay aligned during the curing process of the substrate.

FIGS. 5A-5Cillustrate another embodiment of an output transducer assembly26that is encompassed by the present invention. As shown, the activatable elements34are in the form of elongated magnetic elements. Similar toFIGS. 4A-4C, the poles of the magnetic elements are substantially aligned with each other. The elongated magnetic elements provide a reduced magnetic moment in the plane of the tympanic membrane than the particle magnets ofFIG. 4. Thus the elongated magnetic elements34ofFIG. 5Bare substantially aligned and oriented such that there is a force (upon activation) in a direction that is substantially orthogonal to the tympanic membrane.FIG. 5Cillustrates the elongated magnetic elements in more detail. WhileFIG. 5Cshows each of the elongated magnetic elements having a similar length and width, each of the elongated magnetic elements in the output transducer assembly26may have the same dimensions as each other or they may be different.

In one particular configuration, the elongated magnetic elements have dimensions less than or equal to 0.6 mm×0.2 mm×0.13 mm (W×L×H). Such elongated magnetic elements are sold by Seiko Corp. (See http://www.siimp.cojp/product/detail_e101.html). Of course, other embodiments of the present invention may have dimensions that are smaller or larger than the described embodiments. Larger magnetic elements require greater inter-magnet distances while smaller magnets result in greater packing density of the magnets.

FIGS. 6A and 6Billustrate a configuration in which all of the activatable elements34(e.g., elongated or non-elongated magnets) are aligned radially from a peripheral edge of the tympanic membrane16to a center of the tympanic membrane16. In the embodiment illustrated inFIG. 6A, the magnetic elements34of one type may be configured to be in a wedge shape pattern so as to be specifically tuned to a quadrant of the eardrum. As shown byFIG. 6B, similar toFIG. 5B, the magnetic elements34are substantially aligned and oriented such that there is a force (upon activation) in a direction that is substantially orthogonal to the tympanic membrane16.

If desired, slightly different dimensions or types of magnetic elements may be used for other quadrants and/or different material stiffness for the support component30may be used to appropriately tune the other quadrants of the tympanic membrane. The resonant frequency of a structure is proportional to the square root of the stiffness-to-mass-ratio. By controlling these parameters, the posterior quadrant can be designed to preferentially respond to low frequencies while the anterior quadrant can be designed to respond better at high frequencies. The stiffness of the support structure is controlled depositing elastic material with the desired elastic modulus in the different quadrants, while the mass is controlled by the size and number of magnetic elements.

WhileFIGS. 4A to 6Dillustrate the activatable elements34embedded within the support component, the present invention further encompasses embodiments in which the activatable elements are placed on one or more surfaces of the support component30or are embedded within another substrate that is then coupled to one or more surfaces of the support component30.FIGS. 6C and 6Dillustrate an example where the small distributed magnets of the present invention are combined with a larger central magnet on the support element. The central magnet serves to efficiently drive the tympanic membrane at low frequencies while the distributed magnets efficiently drive the tympanic membrane at the higher frequencies.

FIG. 7Aillustrates a simplified hearing system40of the present invention. The hearing systems40constructed in accordance with the principles of the present invention generally comprise an input transducer assembly42, a transmitter assembly44, and any of the output transducer assemblies26described herein. The input transducer assembly42will receive a sound input, typically either ambient sound (in the case of hearing aids for hearing impaired individuals) or an electronic sound signal from a sound producing or receiving device, such as the telephone, a cellular telephone, a radio, a digital audio unit, or any one of a wide variety of other telecommunication and/or entertainment devices. The input transducer assembly42sends a signal to the transmitter assembly44where the transmitter assembly44processes the signal to produce a processed signal which is modulated in some way, to represent or encode a sound signal which substantially represents the sound input received by the input transducer assembly42. The exact nature of the processed output signal will be selected to be used by the output transducer assembly26to provide both the power and the signal so that the output transducer assembly26can produce mechanical vibrations, acoustical output, pressure output, (or other output) which, when properly coupled to a subject's hearing transduction pathway, will induce neural impulses in the subject which will be interpreted by the subject as the original sound input, or at least something reasonably representative of the original sound input.

In the case of hearing aids, the input transducer assembly42typically comprises a microphone in a housing or shell that is disposed within the auditory ear canal17. While it is possible to position the microphone behind the pinna, in the temple piece of eyeglasses, or elsewhere on the subject, it is preferable to position the microphone within the ear canal (as described in copending application “Hearing System having improved high frequency response”, Ser. No. 11/121,517 filed to May 3, 2005, the full disclosure of which has been previously incorporated herein by reference). Suitable microphones are well known in the hearing aid industry and are amply described in the patent and technical literature. The microphones will typically produce an electrical output that is received by the transmitter assembly44, which in turn will produce a processed digital signal. In the case of ear pieces and other hearing systems, the sound input to the input transducer assembly42will typically be electronic, such as from a telephone, cell phone, a portable entertainment unit, or the like. In such cases, the input transducer assembly42will typically have a suitable amplifier or other electronic interface which receives the electronic sound input and which produces a filtered electronic output suitable for driving the transmitter assembly44and output transducer assembly26.

The transmitter assembly44of the present invention typically comprises a digital signal processor that processes the electrical signal from the input transducer and delivers a signal to a transmitter element that produces the processed output signal that actuates the output transducer assembly26. In one embodiment, the transmitter element that is in communication with the digital signal processor is in the form of a coil that has an open interior and a core sized to fit within the open interior of the coil. A power source is coupled to the coil to supply a current to the coil. The current delivered to the coil will substantially correspond to the electrical signal processed by the digital signal processor. One useful electromagnetic-based assembly is described in commonly owned, copending U.S. patent application Ser. No. 10/902,660, filed Jul. 28, 2004, entitled “Improved Transducer for Electromagnetic Hearing Devices,” the complete disclosure of which is incorporated herein by reference. As can be appreciated, the present invention is not limited to electromagnetic transmitter assemblies, and a variety of different transmitter assemblies may be used with the hearing systems of the present invention.

FIG. 7Bshows a more detailed hearing system40that embodies the present invention. In such embodiments, some of the ambient sound entering the auricle and ear canal17is captured by the input transducer assembly42(e.g., microphone) that is positioned within the open ear canal17. The input transducer assembly42converts sound waves into analog electrical signals for processing by a digital signal processor (DSP) unit50of the transmitter assembly44. The DSP unit50may optionally be coupled to an input amplifier (not shown) to amplify the electrical signal. The DSP unit50typically includes an analog-to-digital converter51that converts the analog electrical signal to a digital signal. The digital signal is then processed by any number of conventional or proprietary digital signal processors and filters50. The processing may comprise of any combination of frequency filters, multi-band compression, noise suppression and noise reduction algorithms. The digitally processed signal is then converted back to analog signal with a digital-to-analog converter53. The analog signal is shaped and amplified and sent to a transmitter element (such as a coil), which generates a modulated electromagnetic field containing audio information representative of the original audio signal and, directs the electromagnetic field toward the output transducer assembly26that comprises the distributed activatable elements (SeeFIGS. 3A-6B). The output transducer assembly26vibrates in response to the electromagnetic field, thereby vibrating the middle-ear acoustic member to which it is coupled (e.g. the tympanic membrane16inFIG. 2).

As noted above, the hearing system40of the present invention may incorporate a variety of different types of input/output transducer assemblies42,26and transmitter assemblies44. Thus, while the examples ofFIGS. 8A to 9Billustrate electromagnetic signals, the hearing systems of the present invention also encompass assemblies which produce other types of signals, such as acoustic signals, pressure signals, optical signals, ultra-sonic signals, infrared signals, or the like.

The various elements of the hearing system40of the present invention may be positioned anywhere desired on or around the subject. In some configurations, all of the components of the hearing system40are partially disposed or fully disposed within the subject's auditory ear canal17. For example, in one preferred configuration, the input transducer assembly42is positioned in the auditory ear canal so as to receive and retransmit the low frequency and high-frequency three dimensional spatial acoustic cues. If the input transducer assembly was not positioned within the auditory ear canal, (for example, if the input transducer assembly is placed behind-the ear (BTE)), then the signal reaching its input transducer assembly42may not carry the spatially dependent pinna cues, and there is little chance for there to be spatial information particularly in the vertical plane. In other configurations, however, it may be desirable to position at least some of the components behind the ear or elsewhere on or around the subject's body.

FIGS. 8A to 9Billustrate examples of hearing system40that are encompassed by the present invention. In the embodiment illustrated inFIGS. 8A and 8B, the components of the hearing system40of the present invention are disposed within a shell or housing46that is placed within the subject's auditory ear canal17. Typically, the shell46has one or more openings62,64on both a first end and a second end so as to provide an open ear canal and to allow ambient sound (such as low and high frequency three dimensional localization cues) to be directly delivered to the tympanic membrane. Advantageously, the openings62,64in the shell46do not block the auditory canal17and minimize interference with the normal pressurization of the ear. In some embodiments, the shell46houses the input transducer assembly42, the transmitter assembly44, and a battery52. In other embodiments, as shown inFIGS. 9A and 9B, portions of the transmitter assembly and the battery (shown as driver unit70) may be placed behind the ear (BTE), while the input transducer assembly42is positioned in the shell46within the ear canal adjacent output transducer assembly26.

FIG. 8Aillustrates one preferred embodiment of a hearing system40encompassed by the present invention. The hearing system40comprises the transmitter assembly42(illustrated with shell46cross-sectioned for clarity) that is installed in a right ear canal and oriented with respect to the output transducer assembly26removably or permanently coupled to the tympanic membrane16. In the preferred embodiment of the current invention, the output transducer assembly26is positioned against tympanic membrane16at umbo area. The output transducer assembly may also be removably or permanently placed on other acoustic members of the middle ear, including locations on the malleus18, incus20, and stapes22. When placed in the umbo area32of the tympanic membrane16, the output transducer assembly26will be naturally tilted with respect to the ear canal17. The degree of tilt will vary from individual to individual, but is typically at about a 60-degree angle with respect to the ear canal.

Shell46is preferably matched to fit snug in the individual's ear canal so that the transmitter assembly42may repeatedly be inserted or removed from the ear canal and still be properly aligned when re-inserted in the individual's ear. In the illustrated embodiment, shell46is also configured to support a coil49and a core51of the transmitter assembly such that the tip of core51is positioned at a proper distance and orientation in relation to the output transducer assembly26when the transmitter assembly44is properly installed in the ear canal17. This alignment requirement is relaxed with the present distributed and active elements. The core51generally comprises ferrite, but may be any material with high magnetic permeability.

In a preferred embodiment, coil49is wrapped around the circumference of the core51along part or all of the length of the core. Generally, the coil has a sufficient number of rotations to optimally drive an electromagnetic field toward the output transducer assembly26. The number of rotations may vary depending on the diameter of the coil, the diameter of the core, the length of the core, and the overall acceptable diameter of the coil and core assembly based on the size of the individual's ear canal. Generally, the force applied by the magnetic field on the output transducer assembly26will increase, and therefore increase the efficiency of the system, with an increase in the diameter of the core. These parameters will be constrained, however, by the anatomical limitations of the individual's ear. The coil49may be wrapped around only a portion of the length of the core, as shown inFIG. 8A, allowing the tip of the core to extend further into the ear canal17, which generally converges as it reaches the tympanic membrane16.

One method for matching the shell46to the internal dimensions of the ear canal is to make an impression of the ear canal cavity, including the tympanic membrane. A positive investment is then made from the negative impression. The outer surface of the shell is then formed from the positive investment which replicated the external surface of the impression. The coil49and core51assembly can then be positioned and mounted in the shell46according to the desired orientation with respect to the projected placement of the output transducer assembly26, which may be determined from the positive investment of the ear canal and tympanic membrane. In an alternative embodiment, the transmitter assembly44may also incorporate a mounting platform (not shown) with micro-adjustment capability for orienting the coil and core assembly such that the core can be oriented and positioned with respect to the shell and/or the coil. In another alternative embodiment, a CT, MRI or optical scan may be performed on the individual to generate a 3D model of the ear canal and the tympanic membrane. The digital 3D model representation may then be used to form the outside surface of the shell46and mount the core and coil.

As shown in the embodiment ofFIG. 8A, transmitter assembly44typically comprise the digital signal processing (DSP) unit and other components50and a battery52that are placed inside shell46. The proximal end53of the shell46may have opening(s)62and may have the input transducer assembly (microphone)42positioned on the shell46so as to directly receive the ambient sound that enters the auditory ear canal17. An open chamber58provides access to the shell46and transmitter assembly42components contained therein. A pull line60may also be incorporated into the shell46so that the transmitter assembly can be readily removed from the ear canal.

Advantageously, in many embodiments, an acoustic opening62of the shell allows ambient sound to enter the open chamber58of the shell. This allows ambient sound to travel through the open volume58along the internal compartment of the transmitter assembly42and through one or more openings64at the distal end of the shell46. Thus, ambient sound waves may reach and directly vibrate the tympanic membrane16and separately impart vibration on the tympanic membrane. This open-channel design provides a number of substantial benefits. First, the open channel17minimizes the occlusive effect prevalent in many acoustic hearing systems from blocking the ear canal. Second, the open channel allows the high frequency spatial localization cues to be directly transmitted to the tympanic membrane17. Third, the natural ambient sound entering the ear canal16allows the electromagnetically driven effective sound level output to be limited or cut off at a much lower level than with a hearing system that blocks the ear canal17. Finally, having a fully open shell preserves the natural pinna diffraction cues of the subject and thus little to no acclimatization, as described by Hoffman et al. (1998), is required.

FIG. 8Billustrates an alternative embodiment of a transmitter assembly44wherein the microphone42is positioned near the opening of the ear canal on shell46and the coil49is laid on the inner walls of the shell46. The core51is positioned within the inner diameter of the coil46and may be attached to either the shell46or the coil49. In this embodiment, ambient sound may still enter ear canal and pass through the open chamber58and out the ports or openings64to directly vibrate the tympanic membrane16.

Now referring toFIGS. 9A and 9B, an alternative embodiment is illustrated wherein one or more of the DSP unit50and battery52are located external to the auditory ear canal in a driver unit70. Driver unit70may hook on to the top end of the pinna15via ear hook72. This configuration provides additional clearance for the open chamber58of shell46(FIG. 8B), and also allows for inclusion of components that would not otherwise fit in the ear canal of the individual. In such embodiments, it is still preferable to have the microphone42located in or at the opening of the ear canal17to gain benefit of high bandwidth spatial localization cues from the auricle17. As shown inFIGS. 9A and 9B, sound entering the ear canal17is captured by input transducer assembly42(e.g., microphone). The signal is then sent to the DSP unit located in the driver unit70for processing via an input wire in cable74connected to jack76in shell46. Once the signal is processed by the DSP unit, the signal is delivered to the coil46by an output wire passing back through cable74. WhileFIGS. 8A to 9Billustrate hearing systems that provide an open ear canal, it should be appreciated, that the concepts of the present invention are equally beneficial to hearing systems that do not provide an open ear canal.

FIG. 10illustrates a kit that is encompassed by the present invention. The kits100of the present invention include an output transducer assembly26, instructions for use102, and packages104. Output transducer assembly26may be any of the output transducers shown and described above, and the instruction for use (IFU)102will set forth any of the methods described herein. Package104may be any conventional medical device packaging, including pouches, trays, boxes, tubes, or the like. The instructions for use202will usually be printed on a separate piece of paper, but may also be printed in whole or in part on a portion of the packaging104. Optionally, the kits100of the present invention may also comprise the input transducer assembly42and/or the transmitter assembly44.

While the above is a complete description of the preferred embodiments of the present invention, various alternatives, modifications, and equivalents may be used. For example, while the above description focuses on the use of a plurality of permanent magnets that are distributed across the tympanic membrane, it should be appreciated that the concepts of the present invention are equally applicable to other types of hearing systems and other acoustic members in the subject's ear. For example, the systems and methods of the present invention may be used to vibrate or otherwise actuate the subject's ossicular chain, cochlea, malleus, or the like.

The notion of distributed and tuned actuation on the eardrum can also be implemented with optical methods rather than the above electromagnetic methods. In this alternative embodiment, different quadrants of the eardrum are set in motion by an optically sensitive substrate which is actuated with optical signals. A more complete description of such systems and methods is described in U.S. patent application Ser. No. 11/248,459, filed Oct. 11, 2005 entitled “Systems and Methods of Photo-Mechanical Hearing Transduction,” by Pluvinage, published on Aug. 24, 2006 as U.S. Publication No. 2006/0189841, the complete disclosure of which is incorporated herein by reference. Therefore, the above description should not be taken as limiting the scope of the invention which is defined by the appended claims.