DEVICES AND METHODS FOR HEARING
20180014128 · 2018-01-11
Inventors
- Sunil PURIA (Boston, MA, US)
- Micha ROSEN (Tzur Hadassah, IL)
- Jonathan P. FAY (Dexter, MI, US)
- Paul RUCKER (San Francisco, CA, US)
- James Stone (Saratoga, CA)
Cpc classification
H04R2460/09
ELECTRICITY
H04R25/65
ELECTRICITY
H04R25/606
ELECTRICITY
H04R17/00
ELECTRICITY
H04R25/554
ELECTRICITY
International classification
H04R17/00
ELECTRICITY
Abstract
A device to transmit an audio signal to a user comprises a transducer and a support. The support is configured for placement on the eardrum to drive the eardrum. The transducer is coupled to the support at a first location to decrease occlusion and a second location to drive the eardrum. The transducer may comprise one or more of an electromagnetic balanced armature transducer, a piezoelectric transducer, a magnetostrictive transducer, a photostrictive transducer, or a coil and magnet. The device may find use with open canal hearing aids.
Claims
1. A device to inductively transmit an audio signal to a user, the user having an ear comprising an ear canal and an eardrum, the device comprising: a first coil configured to fit in the ear canal; and a transducer configured for placement at least partially against the eardrum, the transducer comprising a second coil wherein the second coil is separated from and adapted to be inductively coupled to the first coil.
2. A device according to claim 1 wherein the transducer further comprises a third coil and wherein the second coil is electrically connected to the third coil.
3. A device according to claim 2 wherein the transducer further comprises a moveable structure configured to move in response to a magnetic field.
4. A device according to claim 3 wherein the moveable structure extends along a first elongate direction and an extension structure extends along a second elongate dimension which is transverse or angled relative to the first elongate dimension.
5. A device according to claim 4 wherein the transducer is a balanced armature transducer.
6. A device according to claim 5 wherein the transducer is coupled to a support at a first location, the support being configured for placement at least partially against the eardrum.
7. A device according to claim 5 wherein the transducer is coupled to the support through at least one compression structure, the compression structure configured to urge the transducer toward the eardrum when the support is positioned against the eardrum.
8. A device according to claim 5 wherein the compression structure comprises one or more springs.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0068]
[0069]
[0070]
[0071]
[0072]
[0073]
[0074]
[0075]
[0076] FIGS. 2C1 to 2C4 show views of the balanced armature transducer as in
[0077]
[0078]
[0079]
[0080]
[0081] FIG. 4A1 shows the coils as in
[0082]
[0083]
[0084] FIGS. 5A1, 5B1, and 5C1 show top views of the armature post end portions of
[0085]
[0086]
[0087]
[0088]
[0089]
[0090]
[0091]
[0092] FIG. 8D1 shows the support of
[0093] FIG. 8D2 shows the support of
[0094] FIG. 8D3 shows a post comprising the at least one structure configured to urge the support toward the eardrum;
[0095] FIG. 8E1 shows a medial view of a support having an outer portion comprising an O-ring and a flange extending from the O-ring configured for placement at least partially over an outer portion of the eardrum comprising the annulus and an inner portion configured for placement over an inner portion of the eardrum to drive the eardrum with the inner portion;
[0096] FIG. 8E2 shows a side view of the assembly as in FIG. 8E1;
[0097]
[0098]
[0099] FIG. 9B1 shows a side view of the support as in
[0100] FIG. 9B2 shows a side view of the support as in
[0101] FIGS. 9C1 and 9C2 shows side and top views, respectively, of a support comprising at least one rigid structure coupled to a transducer with pivot coupling, in accordance with embodiments of the present invention;
[0102] FIG. 9D1 shows transducer reed coupled to a support with a viscous material disposed therebetween, so as to inhibit low frequency loading, for example static loading, of the transducer when the support is coupled to the eardrum, in accordance with embodiments of the present invention;
[0103] FIG. 9D2 shows a transducer reed coupled to a support with a viscous liquid so as to inhibit low frequency loading, for example static loading, of the transducer and occlusion when the support is coupled to the eardrum, in accordance with embodiments of the present invention;
[0104]
[0105]
[0106]
[0107]
[0108]
[0109]
[0110]
DETAILED DESCRIPTION OF THE INVENTION
[0111] Embodiments of the present invention can provide hearing devices which directly couple to at least one of the eardrum or the ossicles such that the user perceives sound with minimal occlusion and feedback, and with improved audio signal transmission. The systems, devices, and methods described herein may find application for hearing devices, for example open ear canal hearing aides. Although specific reference is made to hearing aid systems, embodiments of the present invention can be used in any application in which an audio signal is received, for example, optically or electromagnetically, and converted into a mechanical output.
[0112] As used herein, the umbo of the eardrum encompasses a central portion of the eardrum coupled to the malleus and that extends most medially along the ear canal.
[0113]
[0114] Output transducer assembly 100 may have at least a portion of the device coupled to eardrum TM. Output transducer assembly 100 may comprises an output transducer 130 positioned on support and configured to vibrate in response to audio signals. Based on received signals, output transducer assembly 100 can vibrate the eardrum TM in opposing first direction 111 and second direction 113 to produce a sound output. The received signals will typically be based on an original sound input and may be from a light source such as an LED or a laser diode, an electromagnet, an RF source, or the like. To produce a mechanical vibration on the eardrum TM, output transducer assembly 100 may comprise a coil responsive to the electromagnet, a magnetostrictive element, a photostrictive element, a piezoelectric element, an electromagnetic balanced armature, or the like. When properly coupled to the subject's hearing transduction pathway, the mechanical vibrations caused by audio signal transmission device can induce neural impulses in the subject which can be interpreted by the subject as the original sound input.
[0115] Hearing system 10 may comprise an input transducer assembly, for example, a completely-in-the-canal unit or a behind-the-ear unit 20. Behind-the-ear unit 20 may comprise many components of system 10 such as a speech processor, battery, wireless transmission circuitry, and the like. Output transducer assembly 100 will typically be configured to receive signals from the input transducer assembly, for example, the behind-the-ear unit 20. Behind-the-ear unit 20 may comprise many components as described in U.S. Pat. Pub. Nos. 2007/0100197, entitled “Output transducers for hearing systems;” and 2006/0251278, entitled “Hearing system having improved high frequency response.” The input transducer assembly may be located at least partially behind the pinna P or other sites such as in pinna P or entirely within ear canal EC. The input transducer assembly can receive a sound input, for example an audio sound. With hearing aids for hearing impaired individuals, the input can be ambient sound. The input transducer assembly comprises an input transducer, for example, a microphone 22 which may be positioned in many locations such as behind the ear, if appropriate. Microphone 22 is shown positioned within the ear canal EC near its opening to detect spatial localization cues from the ambient sound. The input transducer assembly can include a suitable amplifier or other electronic interface. The input received by the input transducer assembly may comprise an electronic sound signal from a sound producing or receiving device, such as a telephone, a cellular telephone, a Bluetooth connection, a radio, a digital audio unit, and the like.
[0116] Hearing system 10 can include a signal output source 12. The signal output source 12 can produce an output based on a sound input. The output source 12 may comprise a light source such as an LED or a laser diode, an electromagnet, an RF source, or the like. The signal output source can produce an output based on the sound input. Output transducer assembly 130 comprising output transducer 130 can receive the output source and can produce mechanical vibrations in response. Output transducer 130 may comprise a coil responsive to the electromagnet, a magnetostrictive element, a photostrictive element, a piezoelectric element, or the like. When properly coupled to the subject's hearing transducer pathway, the mechanical vibrations caused by output transducer 130 can induce neural impulses in the subject which can be interpreted by the subject as the original sound input.
[0117]
[0118]
[0119]
[0120] The transducer 130 is coupled to the support 120 at a first location 131 and at a second location 133. The first location 131 may correspond to the location of the umbo UM and be spaced away from the second location 133 by at least about 1 mm. As shown in
[0121] Transducer 130 comprises a center of mass CM. Transducer 130 can be positioned on support 130 such that the transducer center of mass CM is positioned on the support away from the umbo when the support is placed on the eardrum TM. The transducer can extend away from the umbo such that the center of mass CM is located away from the umbo. For example, the center of mass CM can be positioned way from the umbo such that the center of mass is aligned with a handle of the malleus. The transducer may extend away from the umbo toward the wall of the ear canal and away from the malleus such that the center of mass is positioned between the umbo and the wall of the ear canal away from the malleus when the support is placed against the ear canal.
[0122] Alternatively to positioning the second location 133 on the support so as to correspond to the lateral process LP, the second location of the support may correspond to a location of the eardrum away from the lateral process LP, so as to decrease interference from blood flow. Blood vessels can extend within eardrum TM along the malleus toward the umbo. The second location can be positioned to correspond to portions of the eardrum away from the blood vessels that extend along the malleus toward the umbo. For example, the second location 133 can be positioned on the support to extend along the tympanic membrane in an anterior posterior direction, a posterior anterior direction, or an inferior superior direction. The transducer may comprises an elongate dimension extending between the first location and the second location, and the elongate dimension of the transducer can be within a range from about 2 mm to about 5 mm.
[0123]
[0124] The transducer 130 can extend away from the umbo UM and away from visible blood vessels of the eardrum so as to decrease interference from the blood vessels that may extend along the malleus.
[0125] Output transducer assembly 100 can be very energy efficient. The transducer 130 and the support 120 may be configured to provide a sound output of at least 80 dB (SPL) with no more than 5% distortion at 10 kHz with no more than about 1 mW of electrical power input to the transducer 130. The transducer 130 and the support 120 may be configured to provide the sound output of at least 80 dB (SPL) with no more than 5% distortion over a range from about 100 Hz to about 10 kHz with the no more than about 1 mW of electrical power input to the transducer 130. These amounts of efficiency can extend the battery life of the output transducer assembly 100 when the output transducer assembly is coupled to an input transducer assembly, for example, at least one of optically coupled or electromagnetically coupled or electrically coupled, as described herein.
[0126] Referring now to
[0127] The balanced armature 250 can be precisely centered or “balanced” in the magnetic field of the permanent magnet 245. As shown in
[0128]
[0129] As shown in
[0130] When coupled to the support 120 on the eardrum TM with the reed post 285 corresponding to the first location 131 and the portion 242 of the casing 240 corresponding to the second location 133, the transducer 130 may drive the eardrum by causing movement of reed post 285 in opposite directions 290. Such movement may cause a movement of portion 242 of casing 240 in directions 292, which will typically be in directions opposite of directions 290. Movement of portion 242 can be less than the movement of the reed post 285. For example, movement of portion 242 may be no more than about 75% of the movement of the reed post 285 when the transducer 130 drives the eardrum.
[0131] As shown in
[0132] FIGS. 2C1 to 2C4 show views of the balanced armature transducer as in
[0133] As shown by
[0134] The transducer 130 may comprise other transducers such a coil responsive to the electromagnet, a magenetostrictve element, a photostrictive element, a piezoelectric element. These transducers may still be rigidly fixed within a casing and have at least one of a reed or post extending out. The combined mass of the transducer 130, support 120, post 185, casing 40, and input element 270 may comprise a combined mass. The components can be selected and arranged so as to minimize or decrease occlusion and provide comfort to the user. In some embodiments, the combined mass of transducer 130, support 120, post 185, casing 40, and input element 270 may comprise no more than about 120 mg, for example when the support is configured to extend to the bony part BP to support the transducer. The effective combined mass of 120 mg with such embodiments can correspond to a mass of no more than about 60 mg, or less, centered on the umbo. The combined mass of transducer 130, support 120, post 185, casing 40, and input element 270 may comprise no more than about 70 mg, for example when the transducer is positioned on the support such that the second location corresponds to the lateral process LP, such that the combined mass corresponds to a mass of no more than about 35 mg, or less, centered on the umbo. The combined mass of transducer 130, support 120, post 185, casing 40, and input element 270 may comprise no more than about 80 mg, for example when the transducer is positioned on the support such that the second location corresponds to the lateral process LP, such that the combined mass corresponds to a mass of no more than about 40 mg, or less, centered on the umbo. For example, the combined mass may comprise about 40 mg and correspond to about 20 mg centered on the umbo.
[0135] Referring now to
[0136] Referring now to
[0137] Referring now to
[0138]
[0139]
[0140]
[0141] Alternatively or in combination with the post and/or tuning structure, the support may comprise a conformable material to decrease or inhibit pre-loading of the transducer against the eardrum. For example a conformable sponge material such as a viscoelastic memory foam can be coupled to the support and post and/or tuning structure so as to decrease or inhibit static pre-loading of the transducer against the eardrum. Alternatively or in combination, the conformable sponge material may comprise a medical grade silicone foam. The conformable sponge material may absorb static preloading of the transducer post without changing substantially the dynamic frequency response characteristics in the audible hearing range, for example with no more than about a 3 dB change in the dynamic frequency response. The conformable structure to decrease or inhibit low frequency loading, for example static loading, may increase user comfort, for example when the support engages the eardrum and the conformable structure changes shape from a first unloaded configuration to a second statically loaded configuration so as to decrease or inhibit pressure on the eardrum. For example, the end portion 287 of the reed post 285 may comprise the conformable sponge material to couple to the support 120 at the first location 131. The support 120 may also comprise the conformable sponge material, for example.
[0142] As shown in
[0143]
[0144]
[0145] The input element 270, as described above, can be rigidly coupled to housing 240 of the assembly 100, such that the input is supported with the housing 240. Alternatively or in combination, the input element may be affixed to the support.
[0146]
[0147]
[0148] The support 120 can be configured in many ways to couple the transducer 130 to the eardrum. The support 120 may be configured with single molded component comprising an inner portion and an outer portion, each configured to contact the eardrum, as described above. Alternatively, support 120 may comprise two or more components, each configured contact the eardrum. Support 120 may comprise an outer component 830 and an inner component 840. Outer component 830 may comprise recess 810 and may be sized to the ear of the user. For example, outer component 830 may comprise O-ring sized to the eardrum TM of the user. In some embodiments, the sized O-ring can be cut to form recess 810 such that the O-ring comprises a C-ring. The transducer 130 can be affixed to the outer component 830 at second location 133 such that second location 133 corresponds to a portion of the annulus TMA of the eardrum TM. Inner component 840 may be size to fit within the outer component 830. For example outer component 830 may comprise an opening 832 having a dimension across, and inner component 840 may comprise a dimension across that is smaller than the dimension of the opening such that the inner component 840 fits inside the opening. Transducer 130 can be coupled to the inner component 840 comprising first location 131 with structures such as a reed 280 coupled to a post 285 of a balanced armature transducer, as described above. The post 285 may extend through the opening 832 to couple transducer 130 to inner component 840 of support 120. The post and reed may comprise many structures, for example rigid structures. Alternatively or in combination, post 285 may comprise a filament having a cross-section sized to move the eardrum TM in response to movement of reed 280.
[0149] The input element 270, as described above, can be rigidly coupled to housing 240 of the assembly 100, such that the input is supported with the housing 240. Alternatively or in combination, the input element may be affixed to the support.
[0150] FIG. 8D1 shows the support of
[0151] FIG. 8D2 shows the support of
[0152] The at least one structure 820 may comprise many structures configured to couple the transducer to the eardrum. For example, the at least one structure 820 may comprise a spring or an elastic material or a combination thereof. For example the spring may comprise a leaf spring or a coil spring. The at least one structure 820 may comprise an elastic material, such as silicone elastomer configured to stretch and pull the transducer toward the eardrum when the support is positioned on the eardrum. The at least one structure may comprise parallel struts configured to extend across the support to opposing sides of the support. The transducer 130 may pivot about second location 133 to couple to the eardrum. Alternatively or in combination, post 285 may comprise the at least one structure 820, as shown in FIG. 8D3. The at least one structure 820 may comprise one or more of the tuning structures, as described above.
[0153] The above structures of support 120 can be configured in many ways to couple effectively the transducer 130 to the ear of the user. The mass of the balanced armature transducer may comprise a center of mass that can be positioned away from the umbo as described above. The force exerted by the at least one structure 820 can be determined based on empirical studies so as to inhibit occlusion and substantially couple the transducer to the eardrum. For example, the mass of the transducer and force of the at least one structure can be determined so as to match substantially the impedance of the transducer coupled to the eardrum to the impedance of the eardrum, such that energy transmission can be efficient. The force of the at least one structure can be configured so as to couple the transducer to the eardrum, for example without fluid disposed between the support and the eardrum at the inner location of the support, although fluid may be used.
[0154] FIG. 8E1 shows a medial view assembly 100 comprising support 120 having an outer portion 830 comprising an O-ring 830R and a flange 850 extending from the O-ring. The outer portion 830 is configured for placement at least partially over an outer portion of the eardrum comprising the annulus TMA. The support 120 comprises inner portion 840 configured for placement over an inner portion of the eardrum to drive the eardrum with the inner portion. The O-ring 830R can be sized to the ear of the user, for example selected from a plurality of sizes of O-rings and fit to a mold of the user. The flange may comprise many materials suitable for support 120 as described above, and may be coupled to the ear with a fluid comprising a liquid as described above. For example, the flange material comprising a liquid such as silicone may be deposited on the mold to correspond to outer portion 830, and the O-ring positioned on the liquid material and cured thereon. The transducer can be affixed to one or more of the O-ring and flange at second location 133, such that inner portion 840 corresponds to a desired location of the inner portion of the eardrum based on the mold. The second location 133 may correspond to a portion of the annulus away from the malleus ML and the vessels VE of the eardrum TM extending along the malleus. The support material can be deposited on the mold to correspond to inner portion 840 and cured with the post 285 extending thereto. Work in relation to embodiments suggests that positioning the second end 133 away from the malleus may be sufficient to decrease or inhibit substantially user perceptible noise related through blood vessels VE, and it is contemplated that in at least some embodiments the support may not comprise the recess. The outer portion may optionally be formed with recess 810 with material positioned on the mold to form the recess 810 as a concavity extending laterally away from the umbo. Alternatively or in combination, the outer portion 830 comprising O-ring 830R can be cut at a location corresponding to the malleus and vessels VE so as to form a C-ring. Based on the teachings described herein, a person of ordinary skill in the art can conduct empirical studies on patients to determine the position of second location 133 and whether a recess is helpful and the location of the recess when present.
[0155] The input element 270, as described above, can be rigidly coupled to housing 240 of the assembly 100, such that the input is supported with the housing 240. Alternatively or in combination, the input element may be affixed to the support.
[0156] FIG. 8E2 shows a side view of the assembly as in FIG. 8E1. The transducer 830 can be coupled to the outer portion 830 and sized such that inner portion 840 corresponds to an intended inner portion of the eardrum. For example, inner portion 830 may correspond to the umbo. Alternatively, inner portion 830 may correspond to an inner portion of the eardrum TM separated from the umbo. Based on the teachings described herein, a person of ordinary skill in the art can determines suitable configurations of inner portion 840 to couple to the inner portion of the eardrum so as to couple to eardrum TM with decreased interference from blood vessels extending along the malleus ML.
[0157] The assemblies and supports shown in
[0158]
[0159] The input element 270, as described above, can be rigidly coupled to housing 240 of the assembly 100, such that the input is supported with the housing 240. Alternatively or in combination, the input element may be affixed to the support.
[0160]
[0161] The at least one rigid structure 826 can be coupled to the transducer in many ways to couple the transducer to the eardrum. The at least one structure 820 may comprise the rigid support structure 826, such that the first end 822 is coupled to the transducer 130. The at least one of the resilient member or spring may be coupled to the at least one rigid structure to urge the transducer toward the eardrum, as described above.
[0162] Alternatively to or in combination with at least one rigid structure 826, transducer 130 can be driven toward the tympanic membrane TM with a transducer 828, for example a piezoelectric bender, when the assembly receives energy to drive the transducer 130.
[0163] FIG. 9B1 shows a side view of the support as in
[0164] FIG. 9B2 shows a side view of the support as in
[0165] FIGS. 9C1 and 9C2 shows side and top views, respectively, of a support comprising at least one rigid structure 826 coupled to a transducer with pivoting coupling and at least one structure 820 to couple the transducer to the eardrum. The at least one structure 820 comprises a first end 822 and a second end 824. First end 822 can be affixed to transducer 130 and second end 824 can be affixed to the support such that the at least one structure urges the transducer 130 toward the eardrum TM to couple the transducer to the eardrum. Transducer 130 may comprise the balanced armature transducer 230 having a housing 240 as described above. The transducer 830 can move relative to the at least one rigid structure, for example with a pivot movement 133P, so as to couple the transducer to the umbo in response to urging of at least one structure 820.
[0166] FIG. 9D1 shows transducer reed coupled to a support with a viscous material disposed therebetween, so as to inhibit low frequency loading, for example static loading, of the transducer when the support is coupled to the eardrum. The reed 280 comprising a rigid material extends to the post 285, as noted above. The viscous material can be configured in many ways so as to couple the reed to the support 131. For example, the post 285 may comprise the viscous material, for example a viscoelastic material such as memory foam. Alternatively or in combination, the viscous material may comprise a viscous fluid, for example a viscous liquid 910 disposed within a container 920, and the post 285 may extend into the container so as to couple to the support 131 with the liquid. The viscous liquid 920 may comprise many liquids and can comprises a viscosity at least as much as the viscosity of water. For example, water comprises a dynamic viscosity of about 0.89 cP (centi-Poise), and the viscosity can be greater, for example at least about 10 cP, or at least about 100 cP. Suitable viscous liquids include castor oil with a viscosity of about 985 cP, ethylene glycol with a viscosity of about 16 cP, glycerol with a viscosity of about 1500 cP, olive oil with a viscosity of about 81 cP, and pitch with a viscosity of about 2.3×10.sup.11 cP. The viscosity can be within a range from about 1 cP to about 2.3×10.sup.11 cP. The viscosity of the liquid can be selected depending on design parameters such as one or more of the inside diameter of the container, the outside diameter of the post, the clearance between the inside diameter of the container and the outside diameter of the post.
[0167] FIG. 9D2 shows a transducer reed 280 coupled to the support with the viscous liquid 910 so as to inhibit low frequency loading, for example static loading, of the transducer and occlusion when the support is coupled to the eardrum. The post can be affixed to flange having openings 185H formed thereon so as to pass liquid 910 with flow 910F through the holes when the support 131 is coupled to the eardrum TM. The openings in the flange can be formed in many ways, for example with one or more of holes drilled in the flange, an annular opening formed in the flange, or an annular flange supported with spokes.
[0168]
[0169]
[0170] In many embodiments, transducer 860 comprises at least one photodetector, for example photodetector 470 as described above. Transducer 860 can be affixed to the support at a location corresponding to the skin SK disposed over the bony process BP, so as to minimize or decrease occlusion when the support is positioned over the bony process BP. The at least one photodetector may comprise one or more photodetectors as described in U.S. Pat. App. No. 61/177,047, filed May 11, 2009, entitled “Optical Electro-Mechanical Hearing Devices With Combined Power and Signal Architectures”; and U.S. patent application Ser. No. 61/139,520, filed Dec. 19, 2008, entitled “Optical Electro-Mechanical Hearing Devices with Separate Power and Signal Components”. These applications describe beneficial methods and apparatus for optically coupling light to a hearing assembly that can be incorporated in accordance with embodiments of the present invention. For example, the electromagnetic energy EM may comprise a first wavelength of light and a second wavelength of light, and the at least one photo detector may comprise two photo detectors in which a first photodetector is sensitive to a first wavelength of light and the second photodetector is sensitive to a second wavelength of light. Each photo detector can be coupled to the transducer with opposite polarity, such that the transducer is driven in a first direction in response to the first wavelength and a second direction in response to the second wavelength, in which the first direction may be opposite the second direction. Alternatively, the at least one photodetector may comprise a single photodetector, and the single photodetector configured to receive power and signal information from light. Active circuitry may be coupled to the at least one detector and transducer to drive the transducer, and the active circuitry may be supported with the skin SK disposed over the bony process BP.
[0171] An optical component 862 can be affixed to the support to couple light energy to the at least one photodetector. The optical component may comprise one or more of a lens, a refractive lens, a diffractive lens, a prism, a Fresnel lens, or a mirror. The optical component is positioned on the support 120 so as to at least one of refract, diffract or reflect the light signal onto the at least one photodetector. In many embodiments, the optical component positioned on the support in a predetermined orientation so as to efficiently couple light transmitted along the ear canal EC to the at least one photodetector. Alternatively or in combination, the optical component can be mounted adjustably, for example one or more of pivoting or bending.
[0172]
[0173]
[0174]
[0175]
[0176] Connector 894 and connector 880 can be configured in many ways such that circuitry 892 can efficiently drive transducer 130 of assembly 100. For example, the connectors by provide direct electrical contact of electrical conductors such that the amplifier circuitry 892 is coupled to transducer 130 with an electrical connection. Work in relation to embodiments suggests that direct electrical contact and direct coupling to the eardrum TM as described above can be more efficient than conventional acoustic hearing aids with a speaker positioned in the ear canal, for example about ten times as efficient, such that the lifetime of a battery can exceed six months. Alternatively to the direct electrical connection, connector 894 and connector 880 may provide electromagnetic inductive coupling, for example with a core of the module 890 positioned within coil of assembly 100. The module 890 may also be coupled to assembly 100 optically, as described above. The connector 880 may comprise a component of the input element 270.
[0177] The energy storage device 898 may comprise a rechargeable energy storage device that can be recharged in many ways. For example, the energy storage device may be charged with a plug in connector coupled to a super capacitor for rapid charging. Alternatively, the energy storage device may be charged with an inductive coil or with a photodetector as described above. The photodetector detector may be positioned on a proximal end of the module 890 such that the photodetector is exposed to light entering the ear canal EC. The photodetector can be coupled to the energy storage device 898 so as to charge the energy storage device. The photodetector may comprise many detectors, for example black silicone as described above. The rechargeable energy storage device can be provided merely for convenience, as the energy storage device 898 may comprise batteries that the user can replace when module 890 is removed from ear canal EC.
[0178] Experimental Models, Measurements and Simulations.
[0179] Laser Doppler vibration measurements of balanced armature output transducers were used with a mathematical model of the umbo to mathematically model the loaded response of the output transducers on the human ear. Exemplary balanced armature output transducers that were measured included an FK-Flat output transducer and a WBFK-Flat output transducer (wide-band), which are commercially available through Knowles Electronics of Itasca, Ill. The response of the output transducers were mathematically modeled as if the output transducer were supported on the malleus of the ear while the armature or reed of the output transducer exerted a force on the umbo of the ear through a reed post as described above.
[0180]
[0181] The WBFK-Flat output transducer has a smaller size and would fit with a wider range of anatomy. The WBFK-Flat output transducer, however, may not have an output performance as good as the FK-Flat output transducer. The force generated per unit current was 2.55 N/A for the FK-Flat output transducer and 0.98 N/A for the WBFK-Flat output transducer.
[0182] Table 1 below shows exemplary parameters for the mathematical modeling of the loaded response of the FK-Flat output transducer.
TABLE-US-00001 TABLE 1 Exemplary Parameters for FK-Flat Variable Symbol Value Moving “center” mass mg 4 mg (+1.6 mg for equivalent reed) Reference “fixed” mass W 17 mg (−1.6 mg for equivalent reed) Low frequency displacement per volt
[0183] The 17 mg equivalent fixed load and the 6 mg moving load were calculated from a model which can be described as a pinned cantilever with a spring opposite the pin. For an inertial mass of 48 mg, a reed length of 4.2 mm, and a reed post height of 2.2 mm, the equivalent M L2 load can be given by the equation:
M.sub.eg is the mass at the center of the transducer, and x is the acceleration of the output transducer.
[0184] Based on the above equation, for the 48 mg mass, the equivalent load for the model is 17 mg, which can significantly decrease perceived occlusion. In addition to the offset 48 mg mass, the transducer assembly also comprises the 4 mg support and the approximately 2 mg reed post.
[0185] Previous testing of output transducers placed on the eardrum had suggested that a mass of 50 mg or more placed on the eardrum would result in significant occlusion. With an output transducer offset away from the umbo and modeled as a cantilever, the effective occlusion for a 48 mg mass that is offset from the umbo is only about 17 mg. Therefore, occlusion is substantially minimized or decreased with the assembly comprising components positioned on the support for placement away from the umbo when the support is placed on the eardrum.
[0186] Studies are also contemplated to optimize balanced armature transducers, such as the FK-Flat and WBFK-Flat output transducers, and others for use with a support coupled directly to a patient's eardrum. For example, a balanced armature transducer may be optimized to drive a load of a support coupled to the eardrum of a patient. An empirical number of patients, for example 10, may be tested with various designs of balanced armature transducers to determine optimum working ranges of various design parameters. Further, bench studies can be conducted and measurements made to further optimize the design. Such parameters to be optimized can include a size of the balanced armature transducer, its geometry, electrical impedance, the materials from which the balanced armature transducer is made, ferrofluid disposed in a cavity between poles of a magnet of the transducer, a spring constant of a restoring member, the number of turns of a wire of a coil wrapped around the armature of the balanced armature transducer, or the diameter of the wire. The armature may also comprise an opposing mass on an end of the armature opposite the support, such that the armature is balanced when coupled to the support configured for placement against the ear of the patient. The output mechanical impedance of the balanced armature transducer can be matched to an input mechanical impedance of the support, so as to optimize mechanical energy transmission from the balanced armature to the eardrum.
[0187] Experimental studies have been conducted with people and supports comprising balanced armature transducers in accordance with some embodiments as described above. With the embodiment tested, the balanced armature transducer was affixed to the support at a first location corresponding to the umbo and a second location toward at least about 4 mm away from the umbo. In at least one instance experiments the support comprising a balanced armature transducer became decoupled from the eardrum. Although fluid had been placed on the eardrum to couple the support and the transducer to the eardrum, the support decoupled. The user noticed that the slight and tolerable occlusion that was normally present did not occur. This empirical data supports the hypothesis that reduced occlusion can result with transducer supported on an outer portion of the support away from the umbo. This data also indicates that a structure can be provided on the support to urge the transducer toward the eardrum. For example, the structure may comprise an elastic structure, or a resilient structure such as a spring. This urging of the transducer toward the eardrum can improve coupling of the transducer to the eardrum and may decrease substantially, even eliminate, the use of fluid to couple the support to the eardrum.
[0188] Experimental studies have been conducted with people and supports comprising balanced armature transducers in accordance with some embodiments as described above. In at least some instances experiments conducted supports extending over the malleus and contacting the eardrum near the periphery of the eardrum have shown that the user can perceive the pulse of the heart beat, for example with the second end of the transducer positioned over the lateral process. In at least some instances attaching the second end of the transducer to the support at a location of the support away from the malleus has substantially decreased this sensation. Further studies with the recess to decrease contact with tissue comprising vascular structures as described above are contemplated. Alternatively or in combination, the first end of the transducer can be coupled to the support at a location corresponding to an inner portion of the eardrum away from the umbo, which can receive at least some blood with pulsatile flow. Based on the teachings described herein, one of ordinary skill in the art can conduct additional empirical studies to determine the shape of the recess and attachment locations of the transducer to the support so as to inhibit this user perceived sound of the heartbeat.
[0189] While the above is a complete description of the preferred embodiments of the invention, various alternatives, modifications, and equivalents may be used. Therefore, the above description should not be taken as limiting in scope of the invention which is defined by the appended claims.