US20210306777A1

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Publication number: US20210306777A1
Application number: US17/232,070
Authority: US
Inventors: Paul Rucker; Sunil Puria; Jonathan Fay; Micha Rosen
Original assignee: EarLens Corp
Current assignee: EarLens Corp
Priority date: 2008-09-22
Filing date: 2021-04-15
Publication date: 2021-09-30
Also published as: BRPI0919266A2; EP2342905A4; EP3509324A1; KR20110086804A; US8858419B2; KR20160119879A; US20170150275A1; US10237663B2; WO2010033933A1; KR101717034B1; CN102301747B; DK3509324T3; BRPI0918994A2; EP2342905B1; US20180014128A1; US20180213331A1; US12133054B2; US20120039493A1; US10511913B2; US20120014546A1

Abstract

A device to transmit an audio signal to a user may comprise a mass, a piezoelectric transducer, and a support to support the mass and the piezoelectric transducer with the eardrum. The piezoelectric transducer can be configured to drive the support and the eardrum with a first force and the mass with a second force opposite the first force. The device may comprise circuitry configured to receive wireless power and wireless transmission of an audio signal, and the circuitry can be supported with the eardrum to drive the transducer in response to the audio signal, such that vibration between the circuitry and the transducer can be decreased. The transducer can be positioned away from the umbo of the ear to drive the eardrum, for example on the lateral process of the malleus.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent application Ser. No. 15/911,595, filed Mar. 5, 2018; which is a divisional of U.S. patent application Ser. No. 15/042,595, filed Feb. 12, 2016; which is a continuation of U.S. patent application Ser. No. 13/069,282, filed Mar. 22, 2011; which is a continuation of PCT Application No. PCT/US2009/057716, filed Sep. 21, 2009; which claims priority to U.S. Patent Application Nos.: 61/139,526 filed Dec. 19, 2008; 61/217,801 filed Jun. 3, 2009; 61/099,087 filed Sep. 22, 2008; and 61/109,785 filed Oct. 30, 2008; the full disclosures of which are incorporated herein by reference.

STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT

This invention was supported by grants from the National Institutes of Health (Grant No. R44DC008499-02A1). The Government may have certain rights in this invention.

BACKGROUND OF THE INVENTION1. Field of the Invention

The present invention is related to hearing systems, devices and methods. Although specific reference is made to hearing aid systems, embodiments of the present invention can be used in many applications in which a signal is used to stimulate the ear.

People like to hear. Hearing allows people to listen to and understand others. Natural hearing can include spatial cues that allow a user to hear a speaker, even when background noise is present.

Hearing devices can be used with communication systems to help the hearing impaired. Hearing impaired subjects need hearing aids to verbally communicate with those around them. Open canal hearing aids have proven to be successful in the marketplace because of increased comfort and an improved cosmetic appearance. Another reason why open canal hearing aids can be popular is reduced occlusion of the ear canal. Occlusion can result in an unnatural, tunnel-like hearing effect which can be caused by large hearing aids which block the ear canal. In at least some instances, occlusion be noticed by the user when he or she speaks and the occlusion results in an unnatural sound during speech. However, a problem that may occur with open canal hearing aids is feedback. The feedback may result from placement of the microphone in too close proximity with the speaker or the amplified sound being too great. Thus, feedback can limit the degree of sound amplification that a hearing aid can provide. Although feedback can be decreased by placing the microphone outside the ear canal, this placement can result in the device providing an unnatural sound that is devoice of the spatial location information cues present with natural hearing.

In some instances, feedback may be decreased by using non-acoustic means of stimulating the natural hearing transduction pathway, for example stimulating the tympanic membrane, bones of the ossicular chain and/or the cochlea. An output transducer may be placed on the eardrum, the ossicles in the middle ear, or the cochlea to stimulate the hearing pathway. Such an output transducer may be electro magnetically based. For example, the transducer may comprise a magnet and coil placed on the ossicles to stimulate the hearing pathway. Surgery is often needed to place a hearing device on the ossicles or cochlea, and such surgery can be somewhat invasive in at least some instances. At least some of the known methods of placing an electromagnetic transducer on the eardrum may result in occlusion in some instances.

One promising approach has been to place a magnet on the eardrum and drive the magnet with a coil positioned away from the eardrum. The magnets can be electromagnetically driven with a coil to cause motion in the hearing transduction pathway thereby causing neural impulses leading to the sensation of hearing. A permanent magnet may be coupled to the ear drum through the use of a fluid and surface tension, for example as described in U.S. Pat. Nos. 5,259,032 and 6,084,975.

However, there is still room for improvement. For example, with a magnet positioned on the eardrum and coil positioned away from the magnet, the strength of the magnetic field generated to drive the magnet may decrease rapidly with the distance from the driver coil to the permanent magnet. Because of this rapid decrease in strength over distance, efficiency of the energy to drive the magnet may be less than ideal. Also, placement of the driver coil near the magnet may cause discomfort for the user in some instances. There can also be a need to align the driver coil with the permanent magnet that may, in some instances, cause the performance to be less than ideal.

For the above reasons, it would be desirable to provide hearing systems which at least decrease, or even avoid, at least some of the above mentioned limitations of the current hearing devices. For example, there is a need to provide a comfortable hearing device which provides hearing with natural qualities, for example with spatial information cues, and which allow the user to hear with less occlusion, distortion and feedback than current devices.

2. Description of the Background Art

BRIEF SUMMARY OF THE INVENTION

Embodiments of the present invention can provide improved hearing which overcomes at least some of the aforementioned limitations of current systems. In many embodiments, a device to transmit an audio signal to a user may comprise a transducer assembly comprising a mass, a piezoelectric transducer, and a support to support the mass and the piezoelectric transducer with the eardrum. The piezoelectric transducer can be configured to drive the support and the eardrum with a first force and the mass with a second force opposite the first force. This driving of the ear drum and support with a force opposite the mass can result in more direct driving of the eardrum, and can improve coupling of the vibration of transducer to the eardrum. The transducer assembly device may comprise circuitry configured to receive wireless power and wireless transmission of an audio signal, and the circuitry can be supported with the eardrum to drive the transducer in response to the audio signal, such that vibration between the circuitry and the transducer can be decreased. The wireless signal may comprise an electromagnetic signal produced with a coil, or an electromagnetic signal comprising light energy produce with a light source. In at least some embodiments, at least one of the transducer or the mass can be positioned on the support away from the umbo of the ear when the support is coupled to the eardrum to drive the eardrum, so as to decrease motion of the transducer and decrease user perceived occlusion, for example when the user speaks. This positioning of the transducer and/or the mass away from the umbo, for example on the short process of the malleus, may allow a transducer with a greater mass to be used and may even amplify the motion of the transducer with the malleus. In at least some embodiments, the transducer may comprise a plurality of transducers to drive the malleus with both a hinging rotational motion and a twisting motion, which can result in more natural motion of the malleus and can improve transmission of the audio signal to the user.

In a first aspect, embodiments of the present invention provide a device to transmit an audio signal to a user. The user has an ear comprising an ear drum. The device comprises a mass, a piezoelectric transducer, and a support to support the mass and the piezoelectric transducer with the eardrum. The piezoelectric transducer is configured to drive the support and the eardrum with a first force and the mass with a second force opposite the first force.

In many embodiments, the piezoelectric transducer is disposed between the mass and the support.

In many embodiments, the device further comprises at least one flexible structure disposed between the piezoelectric transducer and the mass.

In many embodiments, the piezoelectric transducer is magnetically coupled to the support.

In many embodiments, the piezoelectric transducer comprises a first portion connected to the mass and a second portion connected to the support to drive the mass opposite the support.

In many embodiments, the support comprises a first side shaped to conform with the eardrum. A protrusion can be disposed opposite the first side and affixed to the piezoelectric transducer.

In many embodiments, the device further comprises a fluid disposed between the first side and the eardrum to couple the support to the eardrum. The fluid may comprise a liquid composed of at least one of an oil, a mineral oil, a silicone oil or a hydrophobic liquid. In some embodiments, the support comprises a second side disposed opposite the first side and the protrusion extends from the second side to the piezoelectric transducer.

In many embodiments, the support comprises a first component and a second component. The first component may comprise a flexible material shaped to conform to the eardrum and flex with motion of the eardrum. The second component may comprise a rigid material extending from the transducer to the flexible material to transmit the first force to the flexible material and the eardrum. In at least some embodiments, the rigid material comprises at least one of a metal, titanium, a stainless steel or a rigid plastic, and the flexible material comprises at least one of a silicone, a flexible plastic or a gel.

In many embodiments, the device further comprises a housing, the housing rigidly affixed to the mass to move the housing and the mass opposite the support. In some embodiments, the support comprises a rigid material that extends through the housing to the transducer to move the mass and the housing opposite the support.

In many embodiments, the mass comprises circuitry coupled to the transducer and supported with the support and the transducer. The circuitry is configured to receive wireless power and wireless transmission of the audio signal to drive the transducer in response to the audio signal.

In many embodiments, the piezoelectric transducer comprises at least one of a piezoelectric unimorph transducer, a bimorph-bender piezoelectric transducer, a piezoelectric multimorph transducer, a stacked piezoelectric transducer with a mechanical multiplier or a ring piezoelectric transducer with a mechanical multiplier.

In some embodiments, the piezoelectric transducer comprises the bimorph-bender piezoelectric transducer and the mass comprises a first mass and a second mass. The bimorph bender comprises a cantilever extending from a first end supporting the first mass to a second end supporting the second mass. The support is coupled to the cantilever between the first end and the second end to drive the ear drum with the first force and drive the first mass and the second mass with the second force.

In some embodiments, the piezoelectric transducer comprises the stacked piezoelectric transducer with the mechanical multiplier. The mechanical multiplier comprises a first side coupled to the support to drive the eardrum with the first force and a second side coupled to the mass to drive the mass with the second force.

In some embodiments, the piezoelectric transducer comprises the ring piezoelectric transducer with the mechanical multiplier. The mechanical multiplier comprises a first side and a second side. The first side extends inwardly from the ring piezoelectric transducer to the mass. The second side extends inwardly toward a protrusion of the support. The mass moves away from the protrusion of the support when the ring contracts and toward the protrusion of the support when the ring expands. The ring piezoelectric multiplier may define a center having central axis extending there through. The central protrusion and the mass may be disposed along the central axis.

In some embodiments, the piezoelectric transducer comprises the bimorph bender. The mass comprises a ring having a central aperture formed thereon. The bimorph bender extends across the ring with a first end and a second end coupled to the ring. The support extends through the aperture and connects to the piezoelectric transducer between the first end and the second end to move the support opposite the ring when the bimorph bender bends. The bimorph bender can be connected to the ring with an adhesive on the first end and the second end such that the first end and the second end are configured to move relative to the ring with shear motion when the bimorph bender bends to drive the support opposite the ring.

In another aspect, embodiments of the present invention provide a device to transmit an audio signal to a user. The user has an ear comprising an eardrum. The device comprises a transducer, circuitry coupled to the transducer, and a support configured to couple to the eardrum and support the circuitry and the transducer with the eardrum. The circuitry is configured to receive at least one of wireless power or wireless transmission of the audio signal to drive the transducer in response to the audio signal.

In many embodiments, the transducer is configured to drive the support and the eardrum with a first force and drive the circuitry with a second force opposite the first force.

In many embodiments, the circuitry is rigidly attached to a mass and coupled to the transducer to drive the circuitry and the mass with the first force. In some embodiments, the circuitry is rigidly attached to the mass and coupled to the transducer to drive the circuitry and the mass with the second force.

In many embodiments, the circuitry is flexibly attached to a mass and coupled to the transducer to drive the circuitry and the mass with the first force. In some embodiments, the circuitry is flexibly attached to the mass and coupled to the transducer to drive the circuitry and the mass with the second force.

In many embodiments, the circuitry comprises at least one of a photodetector or a coil supported with the support and coupled to the transducer to drive the transducer with the at least one of the wireless power or wireless transmission of the audio signal.

In many embodiments, the transducer comprises at least one of a piezoelectric transducer, a magnetostrictive transducer, a magnet or a coil.

In another aspect, embodiments of the invention provide a device to transmit an audio signal to a user. The user has an ear comprising an eardrum having a mechanical impedance. The device comprises a transducer and a support to support the transducer with the eardrum. A combined mass of the support and the transducer supported thereon is configured to match the mechanical impedance of the eardrum for at least one audible frequency between about 0.8 kHz and about 10 kHz.

In many embodiments, the combined mass comprises no more than about 50 mg. In some embodiments, the combined mass is within a range from about 10 mg to about 40 mg.

In many embodiments, the combined mass comprises at least one of a mass from circuitry to drive the transducer, a mass from a housing disposed over the transducer or a metallic mass coupled to the transducer opposite the support. In some embodiments, the transducer, the circuitry to drive the transducer, the housing disposed over the transducer and the metallic mass are supported with the eardrum when the support is coupled to the eardrum.

In many embodiments, at least one audible frequency is between about 1 kHz and about 6 KHz.

In many embodiments, the transducer and the mass are positioned on the support to place at least one of the transducer or the mass away from an umbo of the eardrum when the support is placed on the eardrum. This positioning can decrease a mechanical impedance of the support to sound transmitted with the eardrum when the support is positioned on the eardrum.

In many embodiments, the piezoelectric transducer comprises a stiffness. The stiffness of the piezoelectric transducer is matched to the mechanical impedance of the eardrum for the at least one audible frequency.

In many embodiments, the eardrum comprises an umbo and the acoustic input impedance comprises an acoustic impedance of the umbo. The stiffness of the piezoelectric transducer is matched to the acoustic input impedance of the umbo.

In another aspect, embodiments of the present invention provide a device to transmit an audio signal to a user. The user has an ear comprising an eardrum and a malleus connected to the ear drum at an umbo. The device comprises a transducer and a support to support the transducer with the eardrum. The transducer is configured to drive the eardrum. The transducer is positioned on the support to extend away from the umbo when the support is placed on the eardrum.

In many embodiments, a mass is positioned on the support for placement away from the umbo when the support is placed against the eardrum, and the transducer extends between the mass and a position on the support that corresponds to the umbo so as to couple vibration of the transducer to the umbo. The mass can be positioned on the support to align the mass with the malleus away from the umbo when the support is placed against the eardrum.

In many embodiments, the transducer is positioned on the support so as to decrease a first movement of the transducer relative to a second movement of the umbo when the eardrum vibrates and to amplify the second movement of the umbo relative to the first movement of the transducer when the transducer vibrates. In some embodiments, the first movement of the transducer is no more than about 75% of the second movement of the umbo and the second movement of the umbo is at least about 25% more than the first movement of the transducer. The first movement of the transducer may be no more than about 67% of the second movement of the umbo and the second movement of the umbo may be at least about 50% more than the first movement of the transducer.

In many embodiments, the device further comprises a mass, and the transducer is disposed between the mass and the support.

In many embodiments, the support is shaped to the eardrum of the user to position the support on the eardrum in a pre-determined orientation. The transducer is positioned on the support to align the transducer with a malleus of the user with the eardrum disposed between the malleus and the support when the support is placed on the eardrum. In some embodiments, the support comprises a shape from a mold of the eardrum of the user.

In many embodiments, the transducer is positioned on the support to place the transducer away from a tip of the malleus when the support is placed on the eardrum.

In many embodiments, the transducer is positioned on the support to place the transducer away from the tip when the support is positioned on the eardrum. The malleus comprises a head and a handle. The handle extends from the head to a tip near the umbo of the eardrum.

In many embodiments, the transducer is positioned on the support to align the transducer with the lateral process of the malleus with the eardrum disposed between the lateral process and the support when the support is placed on the eardrum. In some embodiments, the support comprises a rigid material that extends from the transducer toward the lateral process to move the lateral process opposite the mass.

In many embodiments, the transducer comprises at least one of a piezoelectric transducer, a magnetostrictive transducer, a photostrictive transducer, a coil or a magnet.

In many embodiments, the transducer comprises the piezoelectric transducer. The piezoelectric transducer may comprise a cantilevered bimorph bender, which has a first end anchored to the support and a second end attached to a mass to drive the mass opposite the lateral process when the support is placed on the eardrum.

In many embodiments, the device further comprises a mass coupled to the transducer and circuitry coupled to the transducer to drive the transducer. The mass and the circuitry is supported with the eardrum when the support is placed on the ear. The support, the transducer, the mass and the circuitry comprise a combined mass of no more than about 60 mg, for example, a combined mass of no more than about 40 mg or even a combined mass of no more than 30 mg.

In another aspect, embodiments of the present invention provide a device to transmit an audio signal to a user. The user has an ear comprising an ear drum. The device comprises a first transducer, a second transducer, and a support to support the first transducer and the second transducer with the eardrum when the support is placed against the eardrum. The first transducer is positioned on the support to couple to a first side of the malleus. The second transducer positioned on the support to couple to a second side of the malleus.

In many embodiments, the first transducer is positioned on the support to couple to the first side of the malleus and the second transducer is positioned on the support to coupled to the second side of the malleus which is opposite the first side of the malleus.

In many embodiments, the support comprises a first protrusion extending to the first transducer to couple the first side of the malleus to the first transducer and a second protrusion extending to the second transducer to couple the second side of the malleus to the second transducer.

In many embodiments, the first transducer and second transducer are positioned on the support and configured to twist the malleus with a first rotation about a longitudinal axis of the malleus when the first transducer and second transducer move in opposite directions. The first transducer and second transducer can be positioned on the support and configured to rotate the malleus with a second hinged rotation when the first transducer and second transducer move in similar directions.

In many embodiments, the device further comprises circuitry coupled to the first transducer and the second transducer. The circuitry is configured to generate a first signal to drive the transducer and a second signal to drive the second transducer. In some embodiments, the circuitry is configured to generate the first signal at least partially out of phase with the second signal and drive the malleus with a twisting motion. The circuitry can be configured to drive the first transducer substantially in phase with the second transducer at a first frequency below about 1 kHz, and the circuitry can be configured to drive the first transducer at least about ten degrees out of phase with the second transducer at a second frequency above at least about 2 kHz.

In many embodiments, the first transducer comprises at least one of a first piezoelectric transducer, a first coil and magnet transducer, a first magnetostrictive transducer or a first photostrictive transducer, and the second transducer comprises at least one of a second piezoelectric transducer, a second coil and magnet transducer, a second magnetostrictive transducer or a second photostrictive transducer.

In another aspect, embodiments of the present invention provide a method of transmitting an audio signal to a user. The user has an ear comprising an eardrum. The method comprises supporting a mass and a piezoelectric transducer with a support on the eardrum of the user and driving the support and the eardrum with a first force and the mass with a second force, the second force opposite the first force.

In many embodiments, the ear comprises a mechanical impedance. The mass, the piezoelectric transducer and the support comprise a combined mechanical impedance. The combined mechanical impedance matches the mechanical impedance of the eardrum for at least one audible frequency within a range from about 1 kHz to about 6 KHz.

In another aspect, embodiments of the present invention provide a method of transmitting an audio signal to a user. The user has an ear comprising an eardrum. The method comprises supporting circuitry and a transducer coupled to the circuitry with the eardrum and transmitting the audio signal with a wireless signal to the circuitry to drive the transducer in response to the audio signal.

In another aspect, embodiments of the present invention provide a method of transmitting an audio signal to a user. The user has an ear comprising an eardrum having a mechanical impedance. The method comprises supporting a transducer and a support coupled to the eardrum with the eardrum. A combined mass of the support and the transducer supported thereon matches the mechanical impedance of the eardrum for at least one audible frequency between about 0.8 kHz and about 10 kHz.

In another aspect, embodiments of the present invention provide a method of transmitting an audio signal to a user. The user has an ear comprising an eardrum and a malleus connected to the ear drum at an umbo. The method comprises supporting a transducer with a support positioned on the eardrum and vibrating the support and the eardrum with the transducer positioned away from the umbo. In many embodiments, a first movement of the transducer is decreased relative to a second movement of the umbo when the eardrum is vibrated and the second movement of the umbo is amplified relative to the first movement of the transducer.

In another aspect, embodiments of the present invention provide a method of transmitting an audio signal to a user. The user has an ear comprising an eardrum and a malleus connected to the eardrum at an umbo. The method comprises supporting a first transducer and a second transducer with a support positioned on the eardrum. The first transducer and the second transducer are driven in response to the audio signal to the twist the malleus such that the malleus rotates about an elongate longitudinal axis of the malleus.

BRIEF DESCRIPTION OF THE DRAWINGS

A hearing aid system using wireless signal transduction is shown inFIG. 1, according to embodiments of the present invention;

FIG. 1 A shows the lateral side of the eardrum andFIG. 1B shows the medial side of the eardrum, suitable for incorporation of the hearing aid system ofFIG. 1;

FIGS. 1C and 1D show the eardrum coupled to the ossicles including the malleus, incus, and stapes, and locations of attachment for the hearing aid system shown inFIG. 1;

FIG. 2 shows the sensitivity of silicon photovoltaics to different wavelengths of light, suitable for incorporation with the system ofFIGS. 1A to 1D;

FIG. 3 shows the mechanical impedance of the eardrum in relation to that of various masses, in accordance with the system ofFIGS. 1A to 2;

FIG. 4 shows a simply supported bimorph bender, in accordance with the systems ofFIGS. 1A to 3;

FIG. 5A shows a cantilevered bimorph bender, in accordance with the system ofFIGS. 1A to 3;

FIG. 5B shows cantilevered bimorph bender which includes a first mass and a second mass, in accordance with the system ofFIGS. 1A to 3;

FIG. 6 shows a stacked piezo with mechanical multiplier, in accordance with the system ofFIGS. 1A to 3;

FIG. 7 shows a narrow ring piezo with a mechanical multiplier, in accordance with the system ofFIGS. 1A to 3;

FIG. 8 shows a ring mass with bimorph piezo, in accordance with the system ofFIGS. 1A to 3;

FIGS. 8A and 8B show a cross-sectional view and a top view, respectively, of a ring mass with bimorph piezo, in accordance with the system ofFIGS. 1A to 3;

FIGS.8B1 and8B2 shows a perspective view of ring mass with a bimorph piezo with flexible structures to couple the bimorph piezo to the ring mass, in accordance with the system ofFIGS. 1 A to3;

FIGS. 8C and 8D show a cross-sectional view and a top view, respectively, of a ring mass with dual bimorph piezo, in accordance with the systems ofFIGS. 1A to 3;

FIG. 8E shows a plot of phase difference versus frequency for the first and second transducers of the dual bimorph piezo ofFIGS. 8C and 8D;

FIG. 9 shows a simply supported bimorph bender with a housing, in accordance with the systems ofFIGS. 1 A to4;

FIG. 9A shows an optically powered output transducer, in accordance with the systems ofFIGS. 1A to 3;

FIG. 9B shows a magnetically powered output transducer, in accordance with the systems ofFIGS. 1A to 3;

FIG. 10 shows a cantilevered bimorph bender placed on the eardrum away from the umbo and on the lateral process, in accordance with the systems ofFIGS. 1A to 3;

FIG. 10A shows an output transducer assembly comprising a cantilevered bimorph bender placed on the ear drum with a mass on the lateral process away from the umbo and an elongate member comprising a cantilever extending from the mass toward the umbo so as to couple to the eardrum at the umbo, in accordance with the systems ofFIGS. 1A to 3;

FIG. 10B shows the cantilevered bimorph bender ofFIG. 10A from another view;

FIG. 11 shows a side view of a transducer comprising two cantilevered bimorph benders placed on different locations on the eardrum, in accordance with the systems ofFIGS. 1A to 3;

FIG. 11A shows two cantilevered bimorph benders placed on the ear drum over the umbo and the lateral process, in accordance with the systems ofFIGS. 1A to 3;

FIGS. 12A-12I show an exemplary graph of simulation results for an output transducers in accordance with the systems ofFIGS. 1A to 3;

FIG. 13A shows a stacked piezo andFIG. 13B shows a plot of displacement per voltage for the stacked piezo ofFIG. 13A;

FIG. 14A shows a series bimorph andFIG. 14B shows a plot of displacement per voltage for the series bimorph ofFIG. 14A;

FIG. 15A shows a single crystal bimorph cantilever andFIG. 15B shows a plot of displacement per voltage for the single crystal bimorph cantilever ofFIG. 15A;

FIG. 16A shows a bimorph on a washer andFIG. 16B shows a plot of displacement per voltage for the bimorph on a washer ofFIG. 16A;

FIG. 17A shows a stacked piezo pair,FIG. 17B shows a plot of displacement per voltage for the stacked piezo pair ofFIG. 17A, andFIG. 17C shows a plot of lever ratio for the stacked piezo pair ofFIG. 17C;

FIG. 18A shows a plot of peak output for a bimorph piezo placed on the umbo, andFIG. 18B shows a plot of feedback for a bimorph piezo placed on the umbo;

FIG. 19A shows a plot of peak output for a bimorph piezo placed on the center of pressure on an eardrum, andFIG. 19B shows a plot of feedback for a biomorph piezo placed on the center of pressure on an eardrum; and

FIG. 20A shows a plot of peak output for a stacked piezo placed on the center of pressure on an eardrum, andFIG. 20B shows a plot of feedback for a stacked piezo placed on the center of pressure on an eardrum.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present invention can provide optically coupled hearing devices 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 a signal is wirelessly received and converted into a mechanical output.

As used herein, the umbo of the eardrum encompasses a portion of the eardrum that extends most medially along the ear canal, so as to include a tip, or vertex of the ear canal. As used herein, a twisting motion and/or twisting encompass a rotation of an elongate body about an elongate axis extending along the elongate body, for example rotation of a rigid elongate bone about an elongate axis of the bone. Twisting as used herein encompasses rotation of the elongate body both with torsion of the elongate body about the elongate axis and also without torsion of the elongate body about the elongate axis. As used herein torsion encompasses a strain, or deformation, that can occur with twisting, such that one part of the elongate body twists, or rotates, more than another part of the elongate body.

FIG. 1 shows a hearing aid system using wireless signal transduction. The hearing system includes an input transducer assembly20 and an output transducer assembly30. Hearing system10 may comprise a behind the ear unit BTE. Behind the ear unit BTE may comprise many components of system10 such as a speech processor, battery, wireless transmission circuitry and input transducer assembly10. Behind the ear unit BTE 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 assembly20 is located at least partially behind the pinna P, although an input transducer assembly may be located at many sites such as in pinna P or entirely within ear canal EC. The input transducer assembly20 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 microphone22. Microphone22 can be positioned in many locations such as behind the ear, if appropriate. Microphone22 is shown positioned within ear canal near the opening to detect spatial localization cues from the ambient sound. The input transducer assembly can include a suitable amplifier or other electronic interface. In some embodiments, the input 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.

Input transducer assembly20 includes a signal output source12 which may comprise an electromagnetic source such as a light source such as an LED or a laser diode, an electromagnet, an RF source, or the like. Alternatively, an amplifier of the input assembly may be coupled to the output transducer assembly with a conductor such as a flexible wire, conductive trace on a flex printed circuitry board, or the like. The signal output source can produce an output signal based on the sound input. Output transducer assembly30 can receive the output source signal and can produce mechanical vibrations in response. Output transducer assembly30 may comprise a transducer responsive to the electromagnetic signal, for example at least one photodetector, a coil responsive to the electromagnet, a magenetostrictve element, a photostrictive element, a piezoelectric element, or the like. When properly coupled to the subject's hearing transduction pathway, the mechanical vibrations caused by output transducer assembly30 can induce neural impulses in the subject which can be interpreted by the subject as the original sound input.

The output transducer assembly30 can be configured to couple to a point along the hearing transduction pathway of the subject in order to induce neural impulses which can be interpreted as sound by the subject. As shown inFIG. 1, the output transducer assembly30 may be coupled to the tympanic membrane or eardrum TM. Output transducer assembly30 may be supported on the eardrum TM by a support, housing, mold, or the like shaped to conform with the shape of the eardrum TM. A fluid may be disposed between the eardrum TM and the output transducer assembly30 such as an oil, a mineral oil, a silicone oil, a hydrophobic liquid, or the like. Output transducer assembly30 can cause the eardrum TM to move in a first direction40 and in a second direction45 opposite the first direction40, such that output transducer assembly30 may cause the eardrum TM to vibrate. Specific points of attachment are described in prior U.S. Pat. Nos. 5,259,032; and 6,084,975, the full disclosures of which are incorporated herein by reference and may be suitable for combination with some embodiments of the present invention.

FIG. 1 A shows structures of the ear suitable for placement of the output transducer assembly from the lateral side of the eardrum TM, andFIG. 1 B shows structures of the ear from the medial side of the eardrum TM. The eardrum TM is connected to a malleus ML. Malleus ML comprises a head H, a manubrium MA, a lateral process LP, and a tip T. Manubrium MA is disposed between head H and tip T and coupled to eardrum TM, such that the malleus ML vibrates with vibration of eardrum TM.

FIG. 1 C. shows output transducer assembly30 coupled to the eardrum TM on the umbo UM to transmit vibration so that the user can perceive sound. Eardrum TM is coupled to the ossicles including the malleus ML, incus IN, and stapes ST. The manubrium MA of the malleus ML can be firmly attached to eardrum TM. The most depressed or concaved point of the eardrum TM comprises the umbo UM. Malleus ML comprises a first axis110, a second axis113 and a third axis115. Incus IN comprises a first axis120, a second axis123 and a third axis125. Stapes ST comprises a first axis130, a second axis133 and a third axis135.

The axes of the malleus ML, incus IN and stapes ST can be defined based on moments of inertia. The first axis may comprise a minimum moment of inertia for each bone. The second axis comprises a maximum moment of inertia for each bone. The first axis can be orthogonal to the second axis. The third axis extends between the first and second axes, for example such that the first, second and third axes comprise a right handed triple. For example first axis110 of malleus ML may comprise the minimum moment of inertia of the malleus. Second axis113 of malleus ML may comprise the maximum moment of inertia of malleus ML. Third axis115 of malleus ML can extend perpendicular to the first and second axis, for example as the third component of a right handed triple defined by first axis110 and second axis113. Further first axis120 of incus IN may comprise the minimum moment of inertia of the incus. Second axis123 of incus IN may comprise the maximum moment of inertia of incus IN. Third axis125 of incus IN can extend perpendicular to the first and second axis, for example as the third component of a right handed triple defined by first axis120 and second axis123. First axis130 of stapes ST may comprise the minimum moment of inertia of the stapes. Second axis133 of stapes ST may comprise the maximum moment of inertia of stapes ST. Third axis135 of stapes ST can extend perpendicular to the first and second axis, for example as the third component of a right handed triple defined by first axis130 and second axis133.

Vibration of the output transducer system induces vibration of eardrum TM and malleus ML that is transmitted to stapes ST via Incus IN, such that the user perceives sound. Low frequency vibration of eardrum TM at umbo UM can cause hinged rotational movement125A of malleus ML and incus IN about axis125. Translation at umbo UM and causes a hinged rotational movement125B of the tip T of malleus ML and hinged rotational movement125A of malleus ML and incus IN about axis125, which causes the stapes to translate along axis135 and transmits vibration to the cochlea. Vibration of eardrum TM, for example at higher frequencies, may also cause malleus ML to twist about elongate first malleus axis110 in a twisting movement110A. Such twisting may comprise twisting movement110B on the tip T of the malleus ML. The twisting of malleus ML about first malleus axis110 may cause the incus IN to twist about first incus axis120. Such rotation of the incus can cause the stapes to transmit the vibration to the cochlea where the vibration is perceived as sound by the user.

With the output transducer assembly positioned over the eardrum TM on the umbo UM, the combined mass of the output transducer assembly can be from about 10 to about 60 mg, for example from about 10 to about 40 mg. In some embodiments, the combined mass comprises no more than about 50 mg. The combined mass may comprise the mass of the support, the transducer, a mass opposite the support and/or the circuitry to receive a wireless signal and drive the transducer. The support can be configured to support the transducer, a mass opposite the support and/or the circuitry to receive a wireless signal and drive the transducer with the eardrum when the support is placed against the eardrum.

FIG. 1D shows output transducer assembly30 coupled on the TM away from umbo UM, for example over the lateral process LP of the malleus ML. Output transducer assembly30 may be placed on other parts of the eardrum as well. Depending on the placement of output transducer assembly30 on the eardrum TM, the mechanical impedance of the output transducer assembly30 and the eardrum TM may vary. Placement of output transducer assembly30 away from the umbo UM allows for increased mass of the lateral process while minimizing occlusion. For example, with placement over the lateral process, the mass of the output transducer assembly may comprise approximately twice the mass as when placed over the umbo without causing occlusion. For example, an output transducer assembly comprising a mass of 60 mg positioned over the lateral process will provide a mechanical impedance and occlusion similar to a 30 mg mass positioned over the umbo. Further the vibration of the transducer at the lateral process is amplified from the lateral process to the umbo, for example by a factor of two due to leverage of the malleus with hinged rotation from the head of the malleus to the tip near the umbo.

The mass of transducer assembly30 for placement away from the umbo can be similar to ranges described above for the configuration placed over the umbo, and may be scaled accordingly. For example, with the output transducer assembly positioned over the eardrum TM away from the umbo UM, for example over the lateral process, the combined mass of the output transducer assembly can be from about 20 to about 120 mg, for example from about 40 to about 80 mg. In many embodiments, the combined mass of output transducer assembly30 over the lateral process can be from about 20 mg to about 60 mg to provide occlusion and transmission losses similar to a mass of about 10 mg to about 30 mg over the umbo.

Output transducer assembly30 may have a number of exemplary specifications for maximum output. Output transducer assembly30 may produce a sound pressure level of up to 106 dB. For example, a sound pressure level of up to at least about 90 dB can be sufficient to provide quality hearing for many hearing impaired users. The “center” of the eardrum, or the umbo, may move at 0.1 um/Pa at 1 kHz and 0.01 um/Pa at 10 kHz. The velocity can be 630 um/s/Pa from about 1 kHz and 10 kHz. The area of the eardrum may be about 100 mm². The ear drum may have an impedance of about 0.2 Ns/m for frequencies greater than 1 kHz, which may be damping in nature, and an impedance of about 1000 N/m for frequencies less than 1 kHz in nature, which may be stiffening in nature. Thus, the power input into the ear at up to 106 dB SPL may be up to about 1 uW.

Output transducer assembly30 may comprise a number of exemplary specifications for frequency response. Output transducer assembly30 can have a frequency response of 100 Hz to 10 kHz. For an open canal system, it may be acceptable if low frequency response rolls off below 1 kHz since most hearing impaired subjects have relatively good low frequency hearing and the natural sound pathway can provide this portion of the sound spectrum. A relatively flat response may be good and it may be ideal if a resonance is generated at 2-3 kHz without affecting response at other frequencies. Variability between subjects may be +/−3 dB. This includes variability due to variable insertions and movement of the transducer with jaw movements. Variability across subjects may be +1-6 dB. Even in low responding subjects may need to have adequate output above their thresholds at all frequencies. Subject based calibrations may likely be problematic for clinicians and best avoided if possible.

Output transducer assembly30 may further comprise a number of other exemplary specifications. For example, output transducer assembly30 may have less than 1 percent harmonic distortion of up to 100 db SPL and less than 10 percent distortion of up to 106 db SPL. Output transducer may have less than 30 dB SPL noise equivalent pressure at the input. Output transducer may provide 15 dB of gain up to 1 kHz and 30 dB of gain above 1 kHz.

I. Power Sources:

Both power and signal may be transmitted to the output transducer assembly30. 1 uW of power into the ear may need to be generated to meet maximum output specifications. Methods of transmitting power may include light (photovoltaic), ultrasound, radio frequency, magnetic resonant circuits.

In exemplary embodiments, a piezoelectric transducer driven by a photovoltaic (PV) cell or a number of photovoltaic (PV) in placed in series. The maximum voltage and current provided by the cells can be limited by the area and the amount of incident light upon them. 70 mW may be a good upper limit for the amount of electrical power available for the output transducer at its maximum output. This power can be limited by the amount of heat that can be dissipated as well as battery life considerations.

LEDs may be about 5% efficient in their conversion of electrical power into light power. The maximum light power coming out of the LEDs may be near 3.5 mW. The light coming out of the LED can cover a broader area than the area of the photovoltaic cell. The broader area may be set based on the movement of the ear canal and the ability to point the light directly at the photovoltaic cells. For example, a spot with a diameter that is twice a wide as a square 3.16 mm×3.16 mm photocell may be used. This spot size would have an area of 31.4 mm²(leading to an optical efficiency of 32%). The photodetector area may comprise two parts—one part to move the transducer in a first direction and another part to move the transducer in a second direction, for example as described in U.S. Pat. App. No. 61/073,271, filed on Jun. 17, 2008, entitled “OPTICAL ELECTRO-MECHANICAL HEARING DEVICES WITH COMBINED POWER AND SIGNAL ARCHITECTURES”, (attorney docket no. 026166-001800US), the full disclosure of which is incorporated herein by reference. This two part photodetector area may further reduce the efficiency by a factor of two to 16%. This efficiency may be improved depending on the result of studies showing how much the motion of the ear canal moves the light as well as the ability to initially point the light down the ear canal. With a 16% efficiency, 560 uW of light power impinges on the surface of each of the two photovoltaics. The device may comprise at least one photo detector, for example as described in U.S. Pat. App. No. 61/073,281, filed Jun. 17, 2008, entitled “OPTICAL ELECTRO-MECHANICAL HEARING DEVICES WITH SEPARATE POWER AND SIGNAL COMPONENTS”, (attorney docket no. 026166-001900US), the full disclosure of which is incorporated by reference.

FIG. 2 shows the sensitivity of silicon photovoltaics to different wavelengths of light. The sensitivity of a photodetector is how much current is produced per unit power of incident light (A/W). InFIG. 2, maximum light intensity of 560 uW may be 336 uA at infrared wavelengths (S=0.6 A/W @ 900-1000 nm) or 224 uA in the “red” range (S=0.4 A/W @ 650 nm). Red LEDs may be more efficient than infrared LEDs, so the increased efficiency of the LEDs may overcome the decreased sensitivity of the photodetector at those wavelengths. The maximum available currents may be in the 220-340 uA range. The voltage characteristic of the photodetector is set by the “diode” action of the junction. Starting a 0.3 V, an increasingly non-linear voltage response may be encountered. Hence the maximum effective voltage of the photodetector for our application may be 0.4V. Multiplying this 0.4V by the 224 uA one obtains 90 uW. Taking this 90 uW and dividing by the 560 uW of light power in gives an efficiency of 16%. One may also use the photocells in series to increase the amount of voltage available. However, the area of each photocell may need to be reduced to keep the total area the same. This may have the effect that voltage may be traded for current and vice versa, however the total amount of power remains fixed.

The LED/photovoltaic system may supply approximately 224 uA of current and 0.4V. Voltage can be increased by putting cells in series but the voltage increase may be at the proportional cost of current. 90 uW of power may be available to the transducer for producing motion of the eardrum. However, the amount of power utilized can depend on the load characteristics. The optimal load may be a 1800 ohm resistor (0.4V/224 uA). In either the piezoelectric case (capacitive load) or the voice coil case (inductive load), the load impedance may change as a function of frequency. A frequency at which this optimal impedance is matched may be chosen. For the capacitive load case, the system may be current limited above this frequency and voltage limited below this frequency. For the inductive load case, the situation may reverse. In the current limited cases, one may not be able to reach the desired maximum output levels. In the voltage limited regions, driving the system too hard may highly distort the output. If 2 kHz is chosen as the optimal frequency, this impedance may correspond to a capacitance of 44 nF or an inductance of 143 mH. Even with an optimal load attached, the overall efficiency of the optical power transfer is 0.04%. Yet even with this efficiency, the amount of power produced by the PV is 90× greater than what we expect to need to input into the ear.

Table 1 below summarizes the above-mentioned exemplary power specifications.

TABLE 1

EXEMPLARY POWER SPECIFICATIONS FOR OUTPUT TRANSDUCER

Parameter	Formula	Value	Comment

Input Power Maximum		70 mW	May be chosen based on
			magnetic system experience
			with heat and battery life.
LED efficiency		5%	May be based on literature
			and experimental data
Area of illumination	pR²	R = 3.16 mm	May be a reasonable guess
		A = 31.4 mm²	based on what will be
			required for robust
			illumination of photodetectors

Area of photodetectors	$\frac{𝔟^{2}}{2}$	b = 3.16 mm A = 5 mm²	May be based on what area of the eardrum is easily viewable from a mid ear canal location.

			Remember that only half of
			the area is available for each
			photodetectors (hence the
			divide by 2).

Optical efficiency	$\frac{A_{i l l i u m}}{A_{p v}} \times 1 0 0 %$	16%

Maximum optical power	E_opticalE_LEDP_MAX	560 mW
incident on photodetectors
Sensitivity of PV @ IR		0.6 A/W
(−950 nm)
Sensitivity of PV @ Red		0.4 A/W
(−650 nm)
Maximum PV current @ IR	S_pvP_λPV	336 mA
Maximum PV current @ Red	S_pvP_λPV	224 mA
Maximum PV voltage		0.4 V	Maximum voltage for ~ 10%
			distortion. (0.3 V for ~ 1%)
Maximum PV power @ Red	V_PVmaxI_PVmax	90 mW

Optimal Load for PV	$\frac{V_{PV \max}}{I_{PV \max}}$	1800 ohms

Overall efficiency	$\frac{P_{P V}}{P_{\max} •} \times 1 0 0 %$	0.13%

Other power transmission potions may include ultrasonic power transmission, magnetic resonant circuits, and radiofrequency power transmission. For magnetic resonant circuits, the basic concept is to produce two circuits that resonant with each other. The “far” coil should only draw enough power from the magnetic fields to perform its task. Power transfer may be in the 30-40% efficient range.

II. Output Transducer Specifications

In exemplary embodiments, an output transducer may comprise two major characteristics; the physics used to generate motion and the type of reference method used. The choices for the physics used to generate motion can include electromagnetic (voice coils, speakers, and the like), piezoelectric, electrostatic, pryomechanical, photostrictive, magnetostrictive, and the like. Regardless of what physics are used to generate motion, the energy of the motion can be turned into useful motion of the eardrum. In order to produce motion, forces or moments that act against the impedance of the eardrum may be generated. To generate forces or moments, the reaction force or moment is resisted. To resist such forces or movements, a fixed anchor point may be introduced, a floating inertia may be used, for example, utilizing
translational and rotational inertia, or deforming an object so that the boundaries produce a net force that moves the object, i.e., using a deformation transducer.

FIG. 3 is a graph showing the mechanical impedance of the eardrum in relation to that of various masses of 100 mg, 50 mg, 20 mg, and 10 mg. The impedance of the eardrum matches the masses of 100 mg, 50 mg, 20 mg, and 10 mg at frequencies of about 450 Hz, 700 Hz, 1.5 kHz, 3 kHz, respectively. The impedance of the mass can be dependent on the location of the eardrum. By placing the mass away from the umbo, the impedance can be decreased, for example halved, when the mass is positioned on the short or lateral process of the malleus, for example. For example, a mass of 40 mg can have an impedance at 1.5 kHz that is similar to a 20 mg mass so as to match the impedance of the eardrum TM.

Exemplary physical specifications may be placed on the transducer based on the size of the ear canal, the ability of an output transducer to remain in position and the perception of occlusion resulting from having a mass present on the eardrum. Table 2 below show these specifications.

TABLE 2

EXEMPLARY PHYSICAL SPECIFICATIONS
FOR OUTPUT TRANSDUCER

Parameter	Value	Comment

Maximum dimension	<5	mm	If the dimension gets larger, then
in plane with			manipulating the transducer into
annular			place may become difficult

ligament of TM		for physicians and may not fit
		down some ear canals.

Maximum dimension	<2	mm	If the dimension gets larger, then
perpendicular to			the anterior wall that “hangs” over
TM			the TM may begin to get in the way.
Maximum mass	60	mg	A mass of 46 mg may result in
			significant “occlusion”. Other
			embodiments may be able to hold
			more weight. There may be evidence
			that at even this weight gravity
			may shift the position of the
			transducer depending on the
			‘orientation of the head and the
			support to TM coupling.

Output transducer assembly30 may use a piezoelectric element to generate motion. Material properties of exemplary piezoelectric elements are shown in the table 3 below.

TABLE 3

MATERIAL PROPERTIES OF
EXEMPLARY PIEZOELECTRIC ELEMENTS

					TRS	APC
	APC	APC	APC		single	single
	disk bender	Tapecast	stacked	STEMinc	crystal	crystal

Material	APC 855	APC 850	APC	7 × 7 × .2	TRS	APC
			PST 150	SMQA	PMN-PT	PMN-PT
Density	7600	7700	8000	7900	7900	8200
(kg/m3)
Curie	200	360	155	250	166
Temperature
k33	0.76	0.72			0.91	0.92
d31	276	175	290	140	1000	930
(×10-12 m/V)
d33	600	400	640	310	1900	2000
(×10-12 m/V)
E33 (N/m2)	5.10E+10	5.40E+10	5.56E+10	7.30E+10	1.16E+10
relative	3400	1900	5400	1400	7700	4600
dielectric
constant
(Er33)
E11 (N/m2)	5.90E+10	6.30E+10		8.40E+10		2.48E+10
kp	0.68	0.63	0.58		0.92
kt				0.45	0.55	0.6
k31	0.4	0.36		0.34	0.51	0.72

III. Exemplary Output Transducers

Output transducer assembly30 may comprise a piezoelectric based output transducer, for example, a transducer comprising a piezoelectric unimorph, piezoelectric bimorph, or a piezoelectric multimorph. Exemplary output transducers may comprise a simply supported bimorph bender400 as shown inFIG. 4, a cantilevered bimorph bender500 as shown inFIG. 5, a stacked piezo with mechanical multiplier600 as shown inFIG. 6, a disk or narrow ring piezo with a mechanical multiplier700 as shown inFIG. 7 or a ring mass with bimorph piezoelectric transducer800 as shown inFIG. 8.

FIG. 4 shows a simply supported bimorph bender400 suitable for incorporation with transducer assembly30 as described above. Simply supported bimorph bender400 comprises a first mass410a, a second mass410b, a bimorph piezoelectric cantilever420, and a support430. Cantilever420 extends from a first end supporting first mass410ato a second end supporting second mass410b. Cantilever420 is coupled with the support430 comprising a protrusion430pextending from the support to the transducer to couple the support to the transducer between the first and second ends. Support430 may be configured to support the first and second masses410a,410band the bimorph cantilever420 on the eardrum TM. For example, support430 may comprise a mold shaped to conform with the eardrum TM, for example support430 can be shaped with known molding techniques. The portion430aof support430 which is in contact with the fluid that couples to the eardrum TM can be flexible, for example, by comprising a flexible material such as silicone, flexible plastic, a gel, or the like. Other portions of support430, for example protrusion430P may be rigid, for example, by comprising a metal, titanium, a rigid plastic, or the like. Simply supported bimorph bender400 may comprise circuitry which receives an external, wireless signal and causes cantilever420 to change shape. Cantilever420 may push against masses410a,4106 causing a force on the masses410a,410bin a direction445 and also cause a force on support430 in a direction440 opposite direction445. The force on support430 drives the eardrum TM to produce sensations of sound.

FIG. 5A shows a cantilevered bimorph bender500 suitable for incorporation with transducer assembly30 as described above. Cantilevered bimorph bender500 includes a mass510, a bimorph cantilever520 extending from mass510, and a support530 coupled with cantilever520. Support530 may be configured to support mass510 and bimorph cantilever520 on the eardrum TM, which may not be drawn to scale inFIG. 5A. For example, support530 may comprise a mold shaped to conform with the eardrum TM.30 Cantilever520 is coupled with the support530 comprising a protrusion530pextending from the support to the transducer. The portion530aof support530 which is in contact with the eardrum TM can be flexible, for example, by comprising a flexible material such as silicone, flexible plastic, a gel, or the like. Other portions of support530 may be rigid, for example, by comprising a metal, titanium, a rigid plastic, or the like. Cantilevered bimorph bender500 may comprise circuitry configured to receive an external, wireless signal and cause cantilever520 to bend and thus push against mass510. The pushing action causes a force in a direction545 on the mass510 and also a force on the support530 in a direction540 opposite the direction545. The force on the support530 drives the eardrum TM to produce sensations of sound.

Cantilevered bimorph bender500 includes mass510 and cantilever520. Some embodiments may include more than one mass, cantilever, and/or support.

FIG. 5B shows cantilevered bimorph bender550 suitable for incorporation with transducer assembly30 as described above. Bimorph bender550 includes a first mass560aand a second mass560b. A first cantilevered bimorph570ais coupled to first mass560a. A second cantilevered bimorph570bis coupled to second mass560b. A support580 is coupled to the first cantilevered bimorph570aand second, cantilevered bimorphs570b. First cantilevered bimorph570ais coupled with the support580 comprising a protrusion580p. Second cantilevered bimorph570bis coupled with the support580 comprising a protrusion580pb. Support580 may be configured to support masses560a,560band bimorph cantilevers570a,5706 on the eardrum TM, which may not be drawn to scale onFIG. 5B. For example, support580 may comprise a mold shaped to conform with the eardrum TM. The portion580aof support580 which is in contact with the eardrum TM can be flexible, for example, by comprising a flexible material such as silicone, flexible plastic, a gel, or the like. Other portions of support580 may be rigid, for example, by comprising a metal, titanium, a rigid plastic, or the like. Cantilevered bimorph bender550 may comprise circuitry configured to receive an external, wireless signal and cause cantilevers570a,570bto bend and thus push against masses560a,560b, respectively. The pushing action causes force in a direction595 on the masses560a,560band also a force on the support580 in a direction590 opposite the direction595. The force on the support580 causes a translational movement which drives the eardrum TM to produce sensations of sound. Cantilevers570a,570bmay push masses560a,560bin tandem to cause support540 to translate and drive the eardrum TM. Cantilevers570a,570bmay also push masses560a,570bin different orders as to cause a rotational or twisting movement of the support580 and the eardrum TM.

FIG. 6 shows a stacked piezo with mechanical multiplier600 suitable for incorporation with transducer assembly30 as described above. The stacked piezo600 comprises a plurality of piezoelectric elements or a stacked piezoelectric array610, mechanical multiplier620, a mass630, and a support640. The piezoelectric array610 maybe held by mechanical multiplier620. Mechanical multiplier620 is coupled to mass630 on side623 and support640 on side626. Mechanical multiplier620 is coupled with the Support640 comprising a protrusion640pextending from the support to the transducer. Support640 may be configured to support mechanical multiplier620 and the piezoelectric array610 and the mass630 on the eardrum TM, which may not be drawn to scale inFIG. 6. For example, support640 may comprise a mold shaped to conform with the eardrum TM. The portion630aof support630 which is in contact with the eardrum TM can be flexible, for example, by comprising a flexible material such as silicone, flexible plastic, a gel, or the like. Other portions of support640 may be rigid, for example, by comprising a metal, titanium, a rigid plastic, or the like. Stacked piezo600 may comprise circuitry configured to receive an external, wireless signal and cause the piezoelectric array610 to expand or contract along axis650. Mechanical multiplier620 uses leverage to multiply this expansion and contraction and change its direction to a direction along axis655, thereby producing a force a6inst mass—630 and support640. The force on support640 drives the eardrum TM to produce sensations of sound.

FIG. 7 shows a narrow ring piezo with a mechanical multiplier700 suitable for incorporation with transducer assembly30 as described above. The narrow ring piezo700 comprises a piezoelectric ring710, disc-shaped mechanical multiplier720, a mass730, and a support740. Mechanical multiplier720 is coupled to mass730 and support740. Mechanical multiplier720 is coupled with the support740 comprising a protrusion740pextending from the support to the transducer. Support740 may be configured to support mechanical multiplier720 and the piezoelectric ring710 and the mass730 on the eardrum TM. For example, support740 may comprise a mold shaped to conform with the eardrum TM. The portion740aof support740 which is in contact with the eardrum TM can be flexible, for example, by comprising a flexible material such as silicone, flexible plastic, a gel, or the like. Other portions of support740 may be rigid, for example protrusion740P that extends to the bimorph, by comprising a metal, titanium, a rigid plastic, or the like. Mechanical multiplier720 comprises a first side723 and a second side726, the first side723 extends inwardly from piezoelectric ring710 to mass730 and the second side726 extends inwardly from piezoelectric ring710 to support740. Narrow ring piezo700 may comprise circuitry configured to receive an external, wireless signal and cause the piezoelectric ring710 to expand or contract along axis750. Mechanical multiplier720 uses leverage to multiply this expansion and contraction and change its direction to that along axis755, producing a force against mass730 and support740. The force on support740 drives the eardrum TM to produce sensations of sound.

FIG. 8 shows a ring mass with bimorph piezoelectric transducer800 suitable for incorporation with transducer assembly30 as described above. Piezoelectric transducer800 comprises contact elements contact elements815 and818 to connect a washer ring820 to a piezoelectric bimorph810. Ring mass with bimorph piezoelectric transducer800 comprises a piezoelectric bimorph810, contact elements815,818, a washer ring820 which can serve as a mass and which defines an aperture825, and a support830 coupled to the bimorph810, the support830 coupled with bimorph810 and passing through aperture825 at least in part. Bimorph810 may comprise a single crystal bimorph. Support830 may be configured to support bimorph810 on the eardrum TM. For example, support830 may comprise a mold shaped to conform with the eardrum TM. The portion830aof support830 which is in contact with the eardrum TM can be flexible, for example, by comprising a flexible material such as silicone, flexible plastic, a gel, or the like. Other portions of support830, for example protrusion830p, may be rigid, for example, by comprising a metal, titanium, a rigid plastic, or the like. Bimorph810 comprises a first end813 and a second end816. First end813 and second end816 are respectively coupled to ring820 through contact elements815 and818, for example, through the use of an adhesive. Ring mass, with bimorph piezoelectric transducer800 may be coupled to circuitry configured to receive an external, wireless signal and cause bimorph810 to flex in response. Flexion of bimorph810 produces a shearing force or shear motion of first end813 and second end816 relative to washer ring820 and produces a translational force along axis850 so as to drive support830 against the eardrum TM, producing sensations of sound.

FIGS. 8A and 8B show a ring mass with bimorph piezoelectric transducer802 suitable for incorporation with transducer assembly30 as described above.FIG. 8ashows a cross-sectional view of ring mass with bimorph piezoelectric transducer802.FIG. 8bshows a top view of ring mass with bimorph piezoelectric transducer802. Bimorph810 can be directly connected to washer ring820 which can serve as a mass. Bimorph810 is coupled with a support830 comprising a protrusion830pextending from the support to the transducer. Support830 may be configured to support washer bimorph810 and washer820 on the eardrum TM. The portion of support830 which is in contact with the eardrum TM can be flexible, for example, by comprising a flexible material such as silicone, flexible plastic, a gel, or the like. Other portions of support830 may be rigid, for example, the portions may comprise a metal, titanium, a rigid plastic, or the like. For example, support830 may comprise a mold shaped to conform with the eardrum TM. Support830 may be configured so that protrusion830pis directly over the umbo UM. Ring mass with bimorph piezoelectric transducer802 may comprise circuitry configured to receive an external, wireless signal and cause bimorph810 to bend or flex and thus push against washer820. The pushing action causes a force in a direction852 on washer820 and also a force on the support830 in a direction853. The force on the support830 causes a translational movement of the umbo UM which can rotate malleus ML to produce sensations of sound.

FIGS.8B1 and8B2 show perspective views of mass, for example a ring mass, with a piezoelectric transducer, for example a bimorph piezoelectric transducer803, in which the mass is coupled to the piezoelectric transducer with a flexible intermediate structure, for example intermediate element815, suitable for incorporation with transducer assembly30 as described above. The flexible intermediate structure can relax a boundary condition at the edge of the piezoelectric transducer so as to improve performance of the piezoelectric transducer coupled to the mass. Although an elongate rod is shown, the flexible intermediate structure may comprise many known flexible shapes such as coils, spheres and leafs. Bimorph810 is indirectly and flexibly connected to washer ring820. The ends of bimorph810 can be directly connected to intermediate elements815. Intermediate elements815 can in turn be directly connected to washer ring820. Washer ring820 can serve as a mass. The ends of bimorph810 may be rigidly attached to intermediate elements815, for example, via an adhesive or glue. Intermediate elements815 may be rigidly attached to intermediate elements815, for example, via an adhesive or glue. Intermediate elements815 is flexible so as to provide a flexible boundary condition or a flexible connection between bimorph810 and washer ring820. For example, intermediate elements815 may comprise a rod made of a flexible material such as carbon fiber or a similar composite material. Such a flexible material may be more prone to twisting than bending. By providing such a flexible boundary

condition, the force outputted by transducer803 can be greater, for example, twice as great, as the force outputted if bimorph810 were instead directly and rigidly connected to washer ring820.

Bimorph810 is coupled with a support830. Support830 comprises a protrusion830P protruding from the bimorph810 and a support member830E adapted to conform with the eardrum TM. Protrusion830P is coupled to support member830E. For example, protrusion830P can comprise a first magnetic member831 P and support member830E may comprise a complementary second magnetic member831E so that protrusion830P and support member830E are magnetically coupled. Both first magnetic member831 P and second magnetic member831E may comprise magnets. Alternatively, one of first magnetic member831P or second magnetic member831E may comprise a magnet while the other comprises a ferromagnetic material. To position transducer803 on the eardrum TM, support member830E may first be placed on the eardrum TM, followed by the remainder of the transducer803 as guided by first magnetic member831P and second magnetic member831E. The use of magnetism to guide the positioning of transducer803 can reduce a hearing professional's reliance on vision to position transducer803 on the eardrum TM.

Support member830E may comprise a mold shaped to conform with the eardrum TM. Support member830E can comprise a flexible material such as silicone, flexible plastic, a gel, or the like. The portion of support member830E in contact with protrusion830P may be rigid, for example, the portions may comprise a metal, titanium, a rigid plastic, or the like. Support830 may be configured so that protrusion830P is directly over the umbo UM. Transducer803 may also comprise circuitry824. Circuitry824 may be configured to receive an signal, for example, an external, wireless signal. Circuitry824 can cause bimorph810 to bend or flex and thus push against washer820. The pushing action causes a force in a direction852 on washer820 and also a force on the support830 in a direction853. The force on the support830 causes a translational movement of the umbo UM which can rotate malleus ML to produce sensations of sound.

FIGS. 8C and 8D show embodiments that comprise more than one bimorph, for example a ring mass dual bimorph piezoelectric transducer804, suitable for incorporation with transducer assembly30 as described above. Transducer804 may comprise a mass from about 20 mg to about 60 mg, for example about 40 mg. Ring mass with double bimorph piezoelectric transducer804 comprises first transducer, for example first bimorph810aand second transducer, for example second bimorph810b. Malleus ML extends into the ear canal, and first bimorph810aand second bimorph810bmay extend along a line substantially perpendicular to malleus ML, or first bimorph810aand second bimorph810bmay extend along a line oblique to Malleus ML. Bimorph810aand bimorph810bare coupled to a ring or washer820 which comprises a mass. Bimorph810aand bimorph810bare supported by support830 comprising protrusions830paand830pb, which are coupled to bimorph810aand bimorph810b, respectively. The portion of support830 which is in contact with the eardrum TM can be flexible, for example, by comprising a flexible material such as silicone, flexible plastic, a gel, or the like. Other portions of support830 may be rigid, for example comprising a metal, titanium, a rigid plastic, or the like. For example, support830 may comprise a mold shaped to conform with the eardrum TM.

Ring mass with double bimorph piezoelectric transducer804 may comprise circuitry configured to receive an external, wireless signal and cause bimorph810aand bimorph810bto bend and/or flex and thus push against washer820. The wireless signal may comprise a first signal configured to drive first bimorph810aand a second signal configured to drive second bimorph810b. The pushing action of the first transducer in response to the first signal causes a first force in a first direction852aon washer820 and an opposite force on the support830 in an opposite direction853a. The pushing action of the second transducer in response to the second signal causes a second force in a second direction852bon washer820 and an opposite force on the support830 in an opposite direction853b. The force on the support830 in first direction853aand second direction853bcauses a translational movement which drives the eardrum TM to produce sensations of sound.

The dual transducer804 allows the malleus to be driven in more than one dimension, for example with a first translational motion to rotate the malleus with hinged motion about the head of the malleus and second rotational motion to twist the malleus about an elongate axis of the malleus extending from a head of the malleus toward the umbo. When bimorphs810aand810bare flexed at the same time and in the same direction,′ ring-mass-double-bimorph-piezoelectric-transducer804 may work similar to same as ring-mass-double-bimorph-piezoelectric-transducer804. However, flexion of bimorphs810aand810bat different times and/or in different directions or phase may produce a rotational twisting motion along the elongate axis of the malleus with support830 and thus induce rotation at the umbo of eardrum TM. For example, the received external, wireless signal may cause only one of bimorph810aand bimorph810bto bend or flex. Alternatively or in combination, the received external, wireless signal may cause bimorph810ato bend or flex more than bimorph810b, or vice versa, so as to cause a rotational twisting motion of the malleus to occur along with the hinged rotation motion of the malleus to translate the umbo of eardrum TM. Arrows853TW show twisting motion of the malleus at umbo UM with a first rotation of the malleus about an elongate axis of the malleus. Arrows853TR show translational motion of the umbo UM with hinged rotation of the malleus comprising pivoting of the malleus about the head of the malleus. The first transducer and the second transducer can be driven with a signal having a time delay, for example a phase delay of 90 degrees, such that translation movement and twisting of the malleus and umbo occur. Thus, a first portion support830 may translate in a first direction853 and a second portion of support830 may translate in a second direction853bopposite first direction853aso as to rotate the malleus with twisting motion. Thus, the first transducer and the second transducer comprising bimorphs810aand810bcan be driven so as to cause translational movement and a rotational movement of eardrum TM. Hinged rotational movement of the malleus to effect translational movement of the umbo UM may be made at low frequencies less than about 5 kHz, for example frequencies less than about 1 kHz. Rotational twisting movement of the malleus may be made at frequencies greater than about 2 kHz, for example high frequencies greater than 5 kHz.

FIG. 8E shows a plot of phase difference versus frequency for the first and second transducers of the dual bimorph piezo ofFIGS. 8C and 8D. This phase difference can result in increased frequency gain at high frequencies above about 5 kHz, such that the user can hear the high frequency sounds more clearly due to the twisting of the malleus. At a first frequency below about 1 kHz, for example 0.5 kHz, the phase difference between the first transducer and the second transducer is substantially zero. At a second frequency above from about 3 to 6 kHz, for example above about 5 kHz, the phase difference between the first transducer and the second transducer is at least about 10 degrees. For example, at about 9 kHz, the phase difference between the first transducer and the second transducer may comprise about 100 degrees. The phase difference between the first transducer and the second transducer can be provided in many ways, for example with the audio processor as described above, configured to output a first channel to the first transducer and a second channel to the second transducer. The circuitry coupled to the first transducer and the second transducer may be configured to provide the first signal phase shifted from the second signal in response to the audio signal, for example with circuitry comprising at least one of a capacitor, a resistor or an inductor configured to provide a phase shift of the audio signal such that the first signal is phase shifted from the second signal.

FIG. 9 shows simply supported bimorph bender400 housed in a hermetically sealed900 suitable for incorporation with transducer assembly30 as described above. Housing900 may comprise many known biocompatible materials. In many embodiments, an output transducer may comprise a hermetically sealed housing. Housing900 may be rigidly affixed to masses410aand410bwith rigid connections. First mass410ais connecting to housing900 with rigid connections900RA1 and900RA2. Second mass410bis connecting to housing900 with rigid connections900RBI and900RB2. Housing900 can provide additional mass for bimorph420 to push against. A rigid portion430P of support430 extends through housing900 to bimorph420. Hermitically sealed housing900 may be configured for many of the above described transducers, for example piezoelectric at least one of cantilevered bimorph bender500,550, stacked piezo with mechanical multiplier600, disk or narrow ring piezo with a mechanical multiplier700, or transducer800.

FIG. 9B shows an output transducer904 which receives power through magnet and/or electric power transmission suitable for incorporation with transducer assembly30 as described above. Output transducer904 may comprise a piezoelectric transducer, a magnetostrictive transducer, a photostrictive transducer, a coil and a magnet, or the like. Output transducer904 comprises a piezoelectric transducer910 coupled to a mass920B. Piezoelectric transducer910 and mass920B are both supported by support930. Piezoelectric transducer910 may comprise many of the piezoelectric elements described above, for example at least one of a bimorph, a cantilevered bimorph, a stacked piezo, or a disc or ring piezo. Mass920B may be similar to many of the masses as previously discussed. Piezoelectric transducer910 can be powered by an external coil955 which produces a30 magnetic field957 which causes a magnetic field952 and a voltage in coil950. Coil950 is coupled to and powers piezoelectric transducer910. Coil950 can be supported with mass920B, transducer910 and support930. The electromagnetic field957 produced by external coil955 may provide a signal, for example, a signal representative of sound, to coil950. Appropriate variations in magnetic field957 and magnetic filed952 can cause piezoelectric transducer910 to cause vibrations on eardrum TM which may lead to a sensation of sound.

Tables 4 and 5 below show characteristics of exemplary piezoelectric output transducers as described above, including simply supported bimorph bender400, cantilevered bimorph bender500, stacked piezo with mechanical multiplier600, disk or narrow ring piezo with a mechanical multiplier700, and bimorph or wide ring piezo800.

TABLE 4

EXEMPLARY PARAMETERS OF PIEZOELECTRIC
OUTPUT TRANSDUCERS

Variable	Symbol	Comments

Displacement	w	Simply Supported Bimorph - Mid span
at point of		Cantilever Bimorph - Free end
interest		Stack - Free end
		Narrow Ring - Mid radius
		Wide Ring - Outer radius
Beam or stack	L
length
Beam or stack	b	Stack is assumed to have a square
width Wide		cross section
ring outer
radius
Wide ring	a
inner radius
Thickness	h	Bimorph - ½ total thickness
		Stack - single layer thickness
		Ring - total thickness
Number of	n	Bimorph - number of layers in ½ thickness
layers		Stack - total number of layers
		Ring - total number of layers
Piezoelectric	d₃₁, d₃₃
constant.
Elastic moduli	F₁₁, F₁₂
Density	P
Permittivity	E_o	8.854E−12 (F/m)
of free space
Relative	Ē₃₃
permittivity
Applied	ΔV
voltage
Applied	F	Simply Supported Bimorph - Force (N) at mid
force		span
		Cantilever Bimorph - Force (N) at free end
		Stack - Force (N) at free end
		Narrow Ring - Ring load (N/m) at mid radius
		Wide Ring - Ring load (N/m) at outer radius

TABLE 5

EXEMPLARY MECHANICAL FORMULAS FOR PIEZOELECTRIC
OUTPUT TRANSDUCERS

Type	Formulas	Comments

Simply Supported Bimorph Bender 400	Displacement per Volt $\frac{w}{Δ V} = \frac{3}{6} n {d_{3 1} (\frac{L}{h})}^{2}$

	Capacitance $C = 2 n^{2} ɛ_{0} {\bar{ɛ}}_{3 a} b (\frac{L}{H})$

	Stiffness $\frac{F}{w} = 3 2 E_{1 1} b {(\frac{h}{L})}^{a}$

	1^stMechanical Resonance $f_{1} = \frac{{(π)}^{2}}{2_{π}} \sqrt{\frac{E_{11} h^{2}}{3_{ρ} L^{4}}}$

Cantilevered Bimorph Bender 500 Stack (shown with displacement amplifier) 600	Displacement per Volt $\frac{w}{Δ V} = \frac{3}{4} n {d_{3 1} (\frac{L}{h})}^{2}$ Capacitance $C = 2 n^{2} ɛ_{0} {\bar{ɛ}}_{3 3} b (\frac{L}{h})$

	Stiffness $\frac{F}{w} = 2 E_{11} b {(\frac{h}{L})}^{𝔞}$

	1^stMechanical Resonance $f_{1} = \frac{{(1.8 7 5)}^{2}}{2 π} \sqrt{\frac{E_{1 1} h^{2}}{3 ρ L^{4}}}$

Stack (shown with displacement amplifier) 600	Displacement per Volt $\frac{w}{Δ V} = {nd}_{33}$ Stiffness $\frac{F}{w} = \frac{E_{3 3} b^{2}}{L}$ Capacitance $C = \frac{n ɛ_{0} {\bar{ɛ}}_{3 3} b^{2}}{h}$ 1^stMechanical Resonance $f_{1} = \frac{1}{4 L} \sqrt{\frac{E_{3 3}}{ρ}}$	The 1^stmechanical resonance equation may be the ¼ wave “rod” resonance which can tend to be very high. This may not be the first resonance of the system. The most likely 1^stmode may be the mass of the piezo/ref mass in conjunction with the spring of the displacement amplifier or some kind of bending mode.

Narrow Ring (shown with displacement amplifier) 700	Displacement per Volt $\frac{w}{Δ V} = n d_{3 1} (\frac{r_{0}}{h})$ Stiffness $\frac{F}{w} = \frac{E_{1 1} t}{r_{0} (\frac{h}{r_{0}})}$ Capacitance $C = n^{2} ɛ_{0} {\bar{ɛ}}_{3 3} 2 π t (\frac{r_{0}}{h})$	Remember for ring cases that F is a ring load (N/m) that will be summed by the displacement amplifier. The appropriate 1^st mechanical resonance mode may not be clear. Likely the first resonance may either be a bending type mode or a cos(20) mode.

	1⁺ Mechanical Resonance
Wide Ring	Displacement per Volt $\frac{w}{Δ V} = n d_{31} (\frac{b}{h})$

	Stiffness $\frac{F}{w} = \frac{E_{1 1} t}{b} \frac{(b^{2} - a^{2})}{(1 + v) a^{2} + (1 - v) b^{2}}$

	Capacitance $C = n^{2} ɛ_{0} {\bar{ɛ}}_{3 3} \frac{π (b^{2} - a^{2})}{h}$

	1^stMechanical Resonance

FIG. 10 shows an output transducer assembly comprising1000 a cantilevered bimorph bender positioned on a support1010 such that the output transducer assembly is positioned over the lateral process and away from the umbo when the support is placed on the eardrum, suitable for incorporation with transducer assembly30 as described above. Many of the output transducers as described above can be positioned on support1010 so as to couple to the umbo of the eardrum TM with the transducer positioned away from the umbo, for example on the lateral process LP. The output transducer positioned on the support1010 so as to couple to the umbo with the transducer positioned away from the umbo may comprise at least one of a piezoelectric transducer, a magnetostrictive transducer, a photostrictive transducer, a coil or a magnet. Support1010 can be made with known methods of molding to manufacture a support customized to the ear of the user, for example as with the known EarLens. The transducers as described above, for example simply supported bimorph bender400, cantilevered bimorph bender500, cantilevered bimorph bender550, stacked piezo with mechanical multiplier600, ring piezo with mechanical multiplier700 and ring mass with bimorph piezoelectric transducer800 can be positioned on support1010 so as to position the transducer at the desired location on the eardrum when support1010 is placed against tympanic membrane TM. As shown inFIG. 10, the transducer may comprise cantilevered bimorph bender500 on support1010 and coupled to eardrum TM20 over the lateral process LP and away from the umbo UM. Cantilevered bimorph bender500 can be placed on the support so as to align with malleus ML when the support is placed against the eardrum. For example, support530 of cantilevered bimorph bender500 can be positioned on support1010 to conform to the portion of the eardrum TM over the lateral process LP when support1010 is placed against the eardrum TM. In some embodiments, support530 can be placed directly on the eardrum without support1010, for example directly over the lateral process LP. Mass510 of cantilevered bimorph bender500 may be placed along the eardrum away from the umbo U of the eardrum TM so as to decrease a mechanical impedance of the support to sound transmitted with the eardrum TM. Cantilever520 has a first end coupled to mass510 and a second end coupled to support530. Cantilever520 may bend and push against mass510 and cause a force on support530 which drives the lateral process LP of the malleus ML to produce sensations of sound.

FIGS. 10A and 10B show an output transducer. assembly1050 suitable for incorporation with transducer assembly30 as described above and comprising cantilevered bimorph bender500 placed on a support1060 which may be made from a mold of the user's ear. The output transducer positioned on the support1060 may comprise at least one of a piezoelectric transducer, a magnetostrictive transducer, a photostrictive transducer, a coil or a magnet. Support530, mass510 and the elongate member comprising bimorph cantilever520 of bimorph bender500 are positioned on support1060 such that mass510 is positioned away from the umbo and the elongate member is coupled to the umbo when support1060 is placed against eardrum TM. The elongate member, for example bimorph cantilever520, extends from the mass supported on the lateral process to the umbo so as to couple to the motion of the transducer to the eardrum at the umbo. This configuration has the advantage of lowering the mechanical impedance with the mass positioned away from the umbo while providing mechanical leverage with coupling at the umbo.

The mass can be positioned away from the umbo and/or aligned with the malleus ML in many ways so as to reduce the input impedance of the transducer assembly. For example, mass510 can be positioned on support1060 such that mass510 is supported with the lateral process LP when support1060 is placed against the ear. Also cantilevered bimorph bender500 and support530 can be placed directly on the eardrum TM such that mass510 is aligned with malleus ML, for example aligned with lateral process LP. As shown inFIGS. 10A and 10B, mass510 is placed on support1060 over the lateral process LP and support530 is placed on support1060 over the umbo U when support1060 is placed against the eardrum TM. The elongate member comprising bimorph cantilever520 has a first end coupled to mass510 and a second end coupled to support530. Cantilever520 may bend and push against mass510 and cause a force on support530 which drives the tip T of the malleus ML to produce sensations of sound. The length of cantilever520 may be provided with a longer length such that cantilever520 can provide more mechanical leverage while reducing the input impedance of mass510.

FIG. 11 shows two or more transducers positioned on a support1130 so as to rotate the malleus with hinged rotation at low frequencies and twist the malleus at high frequencies and suitable for incorporation with transducer assembly30 as described above. Many of the above described transducers can be placed on support1130. For example, embodiments of cantilevered bimorph bender550 and bimorph or wide ring piezo800 may cause a twisting motion on the eardrum TM and thus the malleus ML. Placement of two or more output transducers, on different parts of the eardrum TM can also produce a rotational or twisting motion on the eardrum TM at the umbo and the malleus ML. The placed output transducers may comprise, for example, at least one of simply supported bimorph bender400, cantilevered bimorph bender500, stacked piezo with mechanical multiplier600, disk or narrow ring piezo with a mechanical multiplier700, and bimorph or wide ring piezo800. For example,FIGS. 11 and 11A show two cantilevered bimorph benders500A and500B configured to couple to the umbo of the eardrum TM on opposite lateral sides over the tip T of malleus ML. Cantilevered bimorph benders500A and500B each comprise masses510A and510B, respectively, and bimorph cantilevers520A and520B, respectively, and may both be supported with a common support530 and/or support1130 which also supports masses510A and510B. Each of bimorph cantilevers520A and520B comprises an elongate member that extends from the mass to the umbo to couple to the eardrum at the umbo. A phase difference, as described above, between bimorphs500A and500B may cause malleus ML to twist. Masses510A and510B are positioned on support1130 such that masses510A and510B are supported with the lateral process when support1130 is placed against eardrum TM. Output transducers may be placed on other areas of the eardrum TM as well, for example at additional locations away from the umbo as described above. In some embodiments, support530 can be coupled directly to eardrum TM, for example without support1130.

Many of the above embodiments can be evaluated on an empirical number of patients, for example 10 patients to optimize the transducers, for example transducer mass, positioning, support and circuitry. For example, experiments can be conducted on an empirical number of ten patients to determine improved coupling of sound with differential movement of the first transducer and second transducer. In addition to testing with patients, the embodiments can be tested with computer simulations and laboratory testing. The below described experiments are merely examples of experiments that can be performed, and a person of ordinary skill in the art will recognize many variations and modifications that can be used to improve and optimize the performance of the transducer devices described herein.

IV. Experimental

For exemplary piezoelectric elements, five key characteristics were looked at as a function of geometric parameters. The five parameters were: 1) minimum manufacturable layer thickness, 2) electrical capacitance, 3) 1st mechanical resonant frequency (if available), 4) low frequency stiffness, and 5) maximum displacement achievable with a photodetector power source. For each exemplary piezoelectric element, a contour plot of the maximum displacement achievable at 2 kHz was made.FIGS. 12A-12I show an exemplary contour map for an embodiment of a back-to-back amplified stack piezoelectric elements, a PZT506 back-to-back stack with displacement amplifier. Similar plots can be made for additional embodiments comprising the simply supported bimorph piezoelectric elements, for example a PZT506 simply supported bimorph, a TRS singly crystal simply supported bimorph, and a PVDF simply supported bimorph piezoelectric elements.FIGS. 12A-12I include combinations of different numbers of photodetectors used to power the piezoelectric element and the width of the piezoelectric element. The displacement shown accounts for the electrical limitations of the photovoltaic power source as well as any mismatch between the impedance of the umbo and the stiffness of the driving piezo. Equation 1 and Table 6 below show the equation for the maximum displacement and the parameter definitions.

\begin{matrix} d_{\max} = (\frac{d}{V}) R (\frac{K_{pz}}{K_{pz} + R^{z} Z_{umbo}}) \min (N_{PD} V_{\max^{'}} \frac{(\frac{L_{\max}}{N_{PD}})}{2 π f_{1} C}) G & Equation 1 \end{matrix}

TABLE 6

EXEMPLARY TEST PARAMETERS

	Parameter	Value

	f_max	Maximum frequency of interest (10 kHz)
	f₁	2 kHz—frequency used to optimize design
	R	Lever ratio
	K_pz	Low frequency stiffness of piezo
	Z_umbo	Impedance of umbo at f₁

	$\frac{d}{v}$	Displacement per volt of a given design

	N_PD	Number of photocells in series
	V_max	Maximum voltage of single photocell (0.4 V)
	I_max	Maximum current of single photocell
		given the illumination constraints (224 uA)
	C	Capacitance of a given design
	min(x, y)	Minimum function which takes the
		minimum of the two arguments (x, y)

On top of the contour map shown, other parameters are shown as “constraint lines”. For example, the minimum manufacturable thickness is represented as a line. Any design point falling below or to the right of this line may be achievable. Any design point falling above or to the left calls for a layer thickness that is not currently available from any of the contacted vendors. Often, only integer numbers of layers are possible. Similarly, the capacitance is shown in a line. Any design falling below or to the right of this line has less than the optimal capacitance for 2 kHz. Any design above or to the left has a higher capacitance. At this point, one must remember that the displacement contours are shown at kHz. At different frequencies, there will be a different optimal capacitance. (Optimizing for higher frequencies will require smaller capacitances.) Designs that have a 1^stmechanical resonance of 10 kHz are shown as a line. Designs to the right have higher resonant frequencies; designs to the left have lower resonant frequencies. Designs that have a low frequency stiffness equal to the umbo stiffness at 10 kHz are shown with a line. Designs to the right have higher stiffnesses; designs to the left have lower stiffnesses. In exemplary embodiments, piezoelectric element parameters that are below and to the right of all the constraint lines while at the same time maximizing location on the displacement contour are chosen. Contour maps can be made for embodiments of bimorph piezoelectric transducers using the parameters set forth in Table 7.

TABLE 7

EXEMPLARY TEST PARAMETERS
FOR BIMORPH PIEZOELECTRICS

		TRS - Single
Parameter	PZT506	Crystal	PVDF

E₁₁	64.5	GPa	11.6	GPa	3.0	GPa
D₃₁	2250	pm/V	1000	pm/V	20	pm/V

Ē₃₃

2250

7700

12

P	8000	Kg/m³	7900	Kg/m³	1780	Kg/m³
Minimum layer	20	um	140	um	2	um
thickness

Lever Ratio

1.0

L	5	mm	5	mm	5	mm

Contour maps can be made for embodiments of simply supported bimorph piezoelectrics using the parameters set forth in Table 8 The bimorph with the greatest displacement that meets all of the constraints may be selected. Exemplary embodiments SSBM1, SSBM2, SSBM3, SSBM4, SSBM5, SSBM6, SSBM7, SSBM8, SSBM12, SSBM15, and SSBM18 give displacements greater than 0.1 um at 2 kHz.

TABLE 8

DISPLACEMENT MEASUREMENTS FOR EXEMPLARY
BIMORPH PIEZOELECTRIC EMBODIMENTS

		Beam	Number of	Beam 1/2	Number	Layer	Maximum
Embodiment	Material	width	photodetectors	thickness	of layers	thickness	displacement

SSBM1	PZT506	0.5 mm	1	120 um	6	20 um	0.15 um
SSBM2	PZT506	0.5 mm	2	120 um	4	30 um	0.16 um
SSBM3	PZT506	0.5 mm	3	120 um	3	40 um	0.15 um
SSBM4	PZT506	1.0 mm	1	100 um	4	25 um	0.15 um
SSBM5	PZT506	1.0 mm	2	100 um	2	50 um	0.15 um
SSBM6	PZT506	1.0 mm	3	100 um	1	100 um	0.12 um
SSBM7	PZT506	1.5 mm	1	100 um	3	33 um	0.12 um
SSBM8	PZT506	1.5 mm	2	100 um	2	50 um	0.14 um
SSBM9	PZT506	1.5 mm	3	100 um	1	100 um	0.09 um
SSBM10	TRS-SC	0.5 mm	1	280 um	2	140 um	0.045 um
SSBM11	IRS-SC	0.5 mm	2	280 um	2	140 um	0.09 um
SSBM12	TRS-SC	0.5 mm	3	280 um	2	140 um	0.13 um
SSBM13	TRS-SC	1.0 mm	1	280 um	2	140 um	0.05 um
SSBM14	TRS-SC	1.0 mm	2	280 um	2	140 um	0.09 um
SSBM15	TRS-SC	1.0 mm	3	230 um	1	230 um	0.10 um
SSBM16	TRS-SC	1.5 mm	1	280 um	2	140 um	0.045 um
SSBM17	TRS-SC	1.5 mm	2	230 um	1	230 um	0.07 um
SSBM18	TRS-SC	1.5 mm	3	230 um	1	230 um	0.10 um
SSBM19	PVDF	2.0 mm	2	210 um	34	6.2 um	0.045 um
SSBM20	PVDF	2.0 mm	3	210 um	16	13.1 um	0.045 um
SSBM21	PVDF	3.0 mm	2	210 um	27	7.8 um	0.04 um
SSBM22	PVDF	3.0 mm	3	210 um	14	15 um	0.04 um

The PZT506 material appears to be the suitable for making the bimorph. Its combination of thin layer thicknesses, high piezoelectric constants and moderate permittivity provides a suitable best output. Also, it appears that a wide range of beams all produce roughly the same output, 0.15 um. Choosing between these options can be based on tradeoffs of manufacturing. For example, layers in the bimorph can be traded-off against segmenting the photodetector.

Contour maps can be made for embodiments of back-to-back amplified stack piezoelectric elements, a TRS single crystal back-to-back stack with displacement amplifier, respectively. A displacement amplified stack piezoelectric elements may comprise a scissor jack with two stacks placed back-to-back pushing outwards. In this configuration, the centerline of the assembly does not move. Therefore, the maximum stack length to consider for displacement purposes is 2.5 mm or half of the maximum allowable dimension. However, the effective capacitance may be needed to account for both stacks. The lever ratio may be limited to be between 1 and 15. In between those limits, the stiffness of the stack can be matched to the impedance of the umbo at 10 kHz. Since the number of layers in a stack is high, the thickness of the glue/electrodes between layers may need to be considered. For example, a glue/electrode layer thickness of 16 um may be used. Like with simply supported bimorph piezoelectric elements above, amplified stack piezoelectric elements were analyzed at a variety of thicknesses and assuming various numbers of photodetectors in series. Neither the stiffness nor the 1^stresonance of the stack was a limiting factor while layer thickness, capacitance and length may be limiting factors.

Table 9 below shows some exemplary ranges of parameters for embodiments of back-to-back amplified stack piezoelectric elements.

TABLE 9

EXEMPLARY TEST PARAMETERS FOR BACK-
TO-BACK STACK PIEZOELECTRICS

		TRS - Single
Parameter	PZT506	Crystal

	P₁₁	64.5	GPa	11.6	GPa
	d₃₈	545	pm/V	1900	pm/V

ε₃₈

2250

7700

ρ	8000	Kg/m³	7900	Kg/m³
Minimum layer	20	um	140	um
thickness

Lever Ratio

1.0 to 15.0

1.0 to 15

	L	2.5	mm	2.5	mm

Table 10 below shows parameters for several embodiments of back-to-back amplified stack piezoelectric elements Both the single crystal material and the PZT506 material appear to have maximum outputs near 0.3 um. Several embodiments of back-to-back amplified stack piezoelectric elements produce similar amounts of displacement. Thus, there may be flexibility in manufacturing.

TABLE 10

DISPLACEMENT MEASUREMENTS FOR EXEMPLARY BACK-
TO-BACK STACK PIEZOELECTRIC EMBODIMENTS

		Number of
	Stack	photode-	Number of	Layer	Maximum
Material	width	tectors	layers	thickness	displacement

PZT506	0.5	mm	1	65	20	um	0.2	um
PZT506	0.5	mm	2	45	40	um	0.23	um
PZT506	0.5	mm	4	25	90	um	0.28	um
PZT506	0.75	mm	1	58	30	um	0.15	um
PZT506	0.75	mm	2	32	65	um	0.18	um
PZT506	0.75	mm	4	16	135	um	0.20	um
PZT506	1.0	mm	1	45	40	um	0.13	um
PZT506	1.0	mm	2	25	70	um	0.15	um
PZT506	1.0	mm	4	12	180	um	0.16	um
TRS-SC	0.5	mm	1	17	140	um	0.1	um
TRS-SC	0.5	mm	2	17	140	um	0.2	um
TRS-SC	0.5	mm	4	14	170	um	0.31	um
TRS-SC	0.75	mm	1	17	140	um	0.14	um
TRS-SC	0.75	mm	2	17	140	um	0.28	um
TRS-SC	0.75	mm	4	9	260	um	0.31	um
TRS-SC	1.0	mm	1	17	140	um	0.15	um
TRS-SC	1.0	mm	2	14	175	um	0.25	um
TRS-SC	1.0	mm	4	7	350	um	0.28	um

Embodiments of piezoelectric elements were also tested using a laser vibrometer to measure the velocity (and hence the displacement) of a target. Data was analyzed to yield displacement per volt and plotted versus frequency. Data was determined using the equations mentioned above and plotted alongside the test data.

A single Morgan stacked as shown inFIG. 13A was tested. The parameters for the single Morgan stack piezo are shown in Table 11 below. A plot of the test data, including displacement versus voltage, is shown inFIG. 13B.

TABLE 11

EXEMPLARY PARAMETERS FOR
MORGAN STACKED PIEZO

	Parameter	Value

	Material	Morgan
		PZT506

	Piezo Dimensions	1 × 1 × 1.8	mm
	Layer Thickness	20	μm

	Number of Layers	50
	Ell	6.45e10
	d33	545e−12
	d31	−225e−12
	Density	8000
	Relative Permittivity	2250
	Kp (coupling factor)	0.70
	Input Voltage	I V

Input Frequency range	100-20000	Hz
Measured capacitance	52	nF
Calculated capacitance	49.8	nF

A Steiner and Martins cofired Piezo series bimorph as shown inFIG. 14A was tested. The parameters for the single Morgan stack are shown in Table 12 below. A plot of the test data, including displacement versus voltage, is shown inFIG. 14B. Affixing the piezo using a flexible material increased the vibrational displacement by a few dB.

TABLE 12

EXEMPLARY PARAMETERS FOR STEINER AND MARTINS
COFIRED PIEZO - SERIES BIMORPH

	Parameter	Value

	Material	STEM Inc
		SMQA
	Piezo Dimensions	7 mm × 7 mm

Layer Thickness

200

μm

	El I	8.6e10
	d33	310e−12
	d31	−140e−12
	Density	7900
	Relative Permittivity	1400
	Kp (coupling factor)	0.58

Input Voltage	1	V
Input Frequency range	100-20000	Hz
Measured capacitance	1.4	nF
Calculated capacitance	1.4	nF

A TRS Single Crystal Bimorph Cantilever as shown inFIG. 15A was tested. The parameters for the single Morgan stack are shown in Table 13 below. The parameters may comprise known parameters and can be measured by one of ordinary skill in the art. A plot of the test data, including displacement versus voltage, is shown inFIG. 15B

TABLE 13

EXEMPLARY PARAMETERS FOR TRS SINGLE
CRYSTAL BIMORPH CANTILEVER

	Parameter	Value

	Material	TRS single
		crystal
	Piezo Dimensions	6 mm × 6 mm

Layer Thickness

140

μm

	E11	1.16e10
	d33	1900e−12
	d31	−1000e−12
	Density	7900
	Relative Permittivity	7700

	Input Voltage	1	V
	Input Frequency range	100-20000	Hz

Measured capacitance

nF

	Calculated capacitance	35	nF

A TRS Single Crystal Bimorph on a washer as shown inFIG. 16A was tested. The parameters for the single Morgan stack are shown in Table 14 below. A plot of the test data, including displacement versus voltage, is shown inFIG. 16B In this test, the resonance is in the predicted frequency but the magnitude is off by nearly 20 dB. The capacitance is also off, so the piezo may be damaged.

TABLE 14

EXEMPLARY PARAMETERS FOR TRS
SINGLE CRYSTAL ON WASHER

	Parameter	Value

	Material	TRS single
	Piezo Dimensions	1 mm × 5 mm

Layer Thickness

140

μm

	Ell	1.16e10
	d33	1900e−12
	d31	−1000e−12
	Density	7900
	Relative Permittivity	7700

Input Voltage	1	V
Input Frequency range	100-20000	Hz
Measured capacitance	3.6	nF
Calculated capacitance	4.2	nF

A stacked piezo pair with V-jack type displacement amplification as shown inFIG. 17A was tested. The parameters for the single Morgan stack are shown in Table 15 below. A plot of the test data, including displacement versus voltage, is shown inFIGS. 17B and 17C. In this test, an additional resonance appears which may most likely a resonance in the mechanical lever.

TABLE 15

EXEMPLARY PARAMETERS FOR STACKED PIEZO PAIR
WITH V-JACK DISPLACEMENT AMPLIFICATION

	Parameter	Value

	Material	Morgan

Piezo Dimensions

1 × 1 × 3.6

mm

Lever angle, lever ratio

	Number of Layers	100
	Ell	6.45e10
	d33	545e−12
	d31	−225e−12
	Density	8000
	Relative Permittivity	2250
	Kp (coupling factor)	0.70

Input Voltage	1	V
Input Frequency range	100-20000	Hz
Measured capacitance	104	nF
Calculated capacitance	99.6	nF

Embodiments of output transducers which were placed on a subject's eardrum were tested. The transducer was wire driven, connected directly to the audiometer to determine the acoustic threshold. In order to reduce the effect of the wires, 48 AWG wire was used between the transducer and a location just outside the ear canal. The position of the transducer was verified by a physician using a video otoscope.

Once in place, the audiometer driven transducer was energized across a 12 kΩ load and the audiometer setting adjusted to reach threshold. The threshold was recorded at each frequency tested. After the testing was complete and the transducer removed from the subject's ear, the transducer was reconnected to the audiometer and the voltage measured. Often, the audiometer setting was increased by 40 dB to make a reliable measurement.

The data collected was converted to pressure equivalent using Minimum Audible Pressure curves and plotted against the specifications, bench-top data and average electromagnetic or EM system output. In all cases, the assumption is that the input to the transducer is 0.4V peak and 75 mW. The bench-top data was determined by measuring the unloaded displacement and comparing to the known displacement of the umbo at each frequency plotted.

In addition to the threshold measurements, the feedback pressure was measured at two locations: at the umbo and at the entrance to the ear canal. Often, the transducer was driven by a laptop running SYSid, and operated at 1 V peak, with the feedback measured with an ER-7c microphone. The resulting data gives a measure of the gain margin for each transducer design/location if the microphone is located either deep in the canal or at the canal entrance.

FIGS. 18A-20B show peak power output and feedback for the tested embodiments of output transducers. Although an idealized target peak power output of 106 dB is shown for purposes of comparison, peak power outputs of less than 106 dB, for example 80 or 90 dB at 10 kHz, can provide improved hearing for many patients.FIGS. 18A and 18B show peak power output and feedback, respectively, of a TRS single crystal bimorph placed on the umbo. The on ear results match the bench top predictions up to 2 kHz, then diverge, with the on-ear results remaining flat up to 12 kHz. The umbo located transducer used a different piezo than the center of pressure located transducer.

FIGS. 19A and 19B show peak power output and feedback, respectively, of a TRS single crystal bimorph placed on the center of pressure of the eardrum. The on ear results match the bench top predictions up to 2 kHz, then diverge, with the on-ear results remaining flat up to 12 kHz. Employing feedback cancellers or other feedback handling techniques, or moving the microphone location can improve the power output and feedback profiles.

FIGS. 20A and 20B show peak power output and feedback, respectively, of a stacked piezo pair with V-jack type displacement amplification placed on the center of pressure of the eardrum. The 100 nF piezo load causes the PV system to be current limited starting at a low frequency. The overall equivalent pressure per volt (when not current limited) is better than the bimorph case by about 20 dB.

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.

Claims

What is claimed is:

1. A device configured for non-surgical placement through an ear canal to transmit a mechanical signal to a user, the user having an ear comprising the ear canal, a lateral process, an umbo, a malleus and an eardrum, the device comprising:

a support configured and shaped to be placed along at least a portion of the lateral surface of the eardrum, the support being manufactured from a mold of the user's ear wherein a first portion of the support is positioned over the lateral process of the user when the support is placed on the user's eardrum and a second portion of the support is positioned over the umbo of the user when the support is placed on the user's eardrum; and

a piezoelectric bimorph bender positioned on the support such that the bimorph bender is aligned with the first portion of the support and extends to the second portion of the support.

2. A device according toclaim 1 wherein the bimorph bender is aligned with the malleus when the support is placed against the user's eardrum

3. A method of transmitting sound to a user, the user having an ear comprising an ear canal, a lateral process, an umbo, a malleus and an eardrum, the device comprising:

positioning a piezoelectric bimorph bender over the lateral process of the user using a support, wherein the bimorph bender is positioned on the support and the support is made from a mold of the user's ear; and

causing a force on the support which drives the lateral process of the malleus to produce sensations of sound.

4. The method ofclaim 3 wherein the bimorph bender extends from the lateral process to the umbo so as to couple the motion of the bimorph bender to the eardrum at the umbo.

5. The method ofclaim 4 wherein the malleus has a tip and the force drives the tip of the malleus to produce the sensations of sound.