ES2353193T3 - IMPLANTABLE AND EXTERNAL HEARING SYSTEMS THAT HAVE A FLOATING MASS TRANSDUCER. - Google Patents

Abstract

A FLOATING MASS TRANSDUCER IS PRESENTED TO INCREASE A PERSON'S HEARING ACUTE. AN INERCIAL VIBRATION IN THE FLOATING MASS TRANSDUCER (100) PRODUCES SOME VIBRATIONS IN THE INTERNAL EAR. IN AN ASPECT OF THE INVENTION, THE FLOATING MASS TRANSDUCER INCLUDES A MAGNET ELEMENT (12) AND AN INSURED COIL (14) INSIDE A BEDROOM (10) THAT COUPLES THE BONE INSIDE THE MIDDLE EAR. THE COIL IS INSURED FIRST TO THE ACCOMMODATION THAN THE MAGNET. THE MAGNET ELEMENT AND THE COIL ARE CONFIGURED SO THAT THE PASSAGE OF AN ALTERNATE ELECTRICAL CURRENT THROUGH THE COIL CAUSES THE VIBRATION OF THE MAGNET ELEMENT AND THE COIL ONE REGARDING THE OTHER. VIBRATION IS CAUSED BY THE INTERACTION OF THE MAGNETIC FIELDS OF THE MAGNET ELEMENT AND THE COIL. SINCE THE COIL IS INSURED TO THE ACCOMMODATION WAY FIRST THAN THE MAGNET ELEMENT, THE VIBRATIONS OF THE COIL MAKE THE ACCOMMODATION VIBRE. THE FLOATING MASS TRANSDUCER CAN GENERATE VIBRATIONS IN INTERNAL ELOID IF IT IS COUPLED TO THE CRANEO OR THROUGH A PIECE FOR THE MOUTH.

Description

BACKGROUND OF THE INVENTION

 The present invention relates to the field of devices and procedures for aiding hearing in people, and in particular to the field of transducers for the production of vibrations in the inner ear. 5

 The seemingly simple act of hearing is something that can easily be taken for granted. Although it seems that we as human beings do not exert any effort to listen to the sounds that surround us, from a physiological point of view, hearing is an impressive undertaking. The hearing mechanism is a complex system of levers, membranes, fluid deposits, neurons and hair cells that must all work together to supply nerve stimuli to the brain, where this information is compiled at the higher level of perception that we consider as sound.

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 Since the human auditory system encompasses a complicated mix of acoustic, mechanical and neurological systems, there is ample opportunity for something to go wrong. Unfortunately, this is often the case. It is estimated that one in ten people suffer some type of hearing loss. Surprisingly, many patients suffering from hearing loss do not take any action in the form of treatment for the condition. In many ways, hearing is increasingly important, as the pace of life and decision-making increase as we move towards an information-based society. Unfortunately for those with hearing problems, success in many social and professional situations may increasingly depend on effective hearing.

 Participants in the field of Auditory Science are well aware of the progress that is being made to help combat hearing loss and also a scientific understanding of auditory processes. Several key projects underway have helped demonstrate the potential of advanced devices to help people with hearing problems. Although it cannot be argued that conventional acoustic hearing aids have not been helpful for many of the hearing problems, the majority of the affected world population, for whatever reason, has rejected their use. Hopefully they will improve as advances are made and alternatives to conventional devices appear today, the number of patients with hearing problems will get the help they need.

 The first hearing device first appeared in Roman times and consisted of a hollow vault "latch" that probably provided approximately 15-20 decibels of sound amplification to the user. Ear trumpets and conversation tubes were widely available in the 1700s and 1800s, and the first electronic hearing aids began to be present in the 1900s. The development of transistor 30 led to smaller and more powerful hearing aids that began to appear in the 1950s. Interestingly, transistor-type hearing aids were the first products of Sony Corporation before advancing to audio equipment. In fact, many inventions, including the telephone, were derivations of hearing aid development.

 In the 1960s and 1970s, hearing aids underwent a period of accelerated development. The hearing aid companies and product lines began to multiply rapidly. Measurement standards for prescribing devices, and standards for the evaluation of patient hearing and hearing aid manufacturing were increasingly consolidated. The audiologists worked to advance in device technology, continuing hearing research and establishing improvements in the measurement of hearing devices and mounting technology. Audiological advances in the evaluation of hearing and the diagnosis of hearing problems resulted in a better diagnosis and treatment for people with hearing difficulties. State regulation of distribution industry 40 through licensing and certification programs was developed to ensure the quality of hearing aid practices.

 Patients with hearing problems in 1995 have a wide variety of hearing devices to choose from. The devices have improved circuits and improved adjustment parameters that allow you to customize the electronics to the individual hearing loss of patients (that is, similar to a prescription for glasses, one size does not fit 45 for everyone). New devices located completely in the ear canal of patients are available that are aesthetically superior to the large bulky devices of recent years and may be virtually invisible. Many manufacturers participate in the hearing market, which is an important world market of 3 billion dollars.

 A series of defects in the auditory system are known to deteriorate or impede the hearing. To illustrate these defects, a schematic representation of a part of the human auditory system is shown in Figure 1. The auditory system generally comprises an outer ear AA, a middle ear JJ, and an inner ear FF. The outer ear AA includes the auditory canal BB and the tympanic membrane CC, and the inner ear FF includes an oval window EE and a GG vestibule which is a passage to the cochlea (not shown). The middle ear JJ is placed between the outer ear and the middle ear, and includes a KK Eustachian tube and three bones called DD ossicles. The three DD ossicles: the hammer LL, the anvil MM and the stirrup HH, are placed between and connected to the tympanic membrane CC and the oval window EE.

 In a person with normal hearing, the sound enters the outer ear AA, where it is slightly amplified by the resonance characteristics of the auditory canal BB. The sound waves produce vibrations in the tympanic membrane CC, part of the outer ear that is placed at the distal end of the ear canal BB. The force of these vibrations is magnified by the DD ossicles.

 On the vibration of the DD ossicles, the oval window EE, which is part of the inner ear FF, conducts the 5 vibrations to the cochlear fluid (not shown) in the inner ear FF, thus stimulating the recipient cells, or hairs, within the cochlea (not shown). The vibrations in the cochlear fluid also drive the vibrations of the round window (not shown). In response to stimulation, the hairs generate an electrochemical signal that is supplied to the brain through one of the cranial nerves, and causes the brain to perceive the sound.

 The vibratory structures of the ear include the tympanic membrane, the ossicles (hammer, anvil and stirrup), the oval window, the round window, and the cochlea. Each of the vibrating structures of the ear vibrates to some degree when a person with normal hearing hears the sound waves. However, hearing loss in a person can be evidenced by one or more vibratory structures that vibrate less than normal or not at all.

 Some patients with hearing loss have ossicles that lack the flexibility necessary to increase the strength of vibrations to a sufficient level that stimulates the recipient cells in the cochlea. Other patients have 15 ossicles that are broken and, therefore, do not lead the sound vibrations to the oval window.

 Sometimes prostheses are implanted for ossicular reconstruction in patients who have partially or completely broken ossicles. These prostheses are designed to fit perfectly between the tympanic membrane CC and the oval window EE or stirrup HH. The tight fit keeps the implants in position, although sometimes the middle ear is filled with gel foam to protect against loosening. Two basic forms are available: total replacement ossicular prosthesis 20 that are connected between the tympanic membrane CC and the oval window EE; and partial replacement ossicular prosthesis that are placed between the tympanic membrane and the HH stirrup. Although these prostheses provide a mechanism by which vibrations can be conducted through the middle ear to the oval window of the inner ear, additional devices are often necessary to ensure that vibrations are delivered to the inner ear with sufficient force to produce a perception of high quality sound. 25

 Various types of hearing aids have been developed to restore or improve hearing for people with hearing difficulties. With conventional hearing aids, sound is detected by a microphone, amplified using an amplification circuit, and transmitted in the form of acoustic energy through a loudspeaker or other type of transducer in the middle ear through the tympanic membrane. Often, the acoustic energy supplied by the speaker is detected by the microphone, causing a sharp whistle of feedback. On the other hand, the amplified sound produced by conventional hearing aids usually includes a significant amount of distortion.

 Attempts have been made to eliminate distortion and feedback problems associated with conventional hearing aid systems. These attempts have produced devices that convert sound waves into electromagnetic fields with the same frequencies as sound waves. A microphone detects sound waves 35, which are amplified and converted into an electric current. A coil winding remains motionless by attaching to a non-vibrating structure in the middle ear. The current is supplied to the coil to generate an electromagnetic field. A magnet is fixed to an ossicle inside the middle ear so that the magnetic field of the magnet interacts with the magnetic field of the coil. The magnet vibrates in response to the interaction of magnetic fields, causing the vibration of the bones of the middle ear. 40

 Existing electromagnetic transducers present several problems. Many are installed using complex surgical procedures that present the usual risks associated with major surgery and that also require dismantling (disconnecting) one or more of the middle ear bones. Disarticulation deprives the patient of any residual hearing that he or she may have had before surgery, placing the patient in a worse position if the implanted device is subsequently found to be ineffective in improving the hearing of the patient.

 Existing devices are also unable to produce vibrations in the middle ear that are substantially linear in relation to the current that is conducted to the coil. Thus, the sound produced by these devices includes a significant distortion because the vibrations conducted in the inner ear do not correspond precisely to the sound waves detected by the microphone. fifty

 An improved transducer, therefore, is necessary, which ultimately produces vibrations in the cochlea that have sufficient force to stimulate auditory perception with minimal distortion.

 US 3,870,832 describes the implantation of a coil and a magnet in the ear after the removal of the anvil, the magnet being attached to the stirrup and the coil producing a magnetic field that causes the stirrup to move in the same way as generally moves through the anvil. 55

  WO95 / 01710 discloses a magnetic transducer for improving hearing that comprises a magnet assembly and a fixed coil inside a housing that is fixed to an ossicle of the middle ear. As the coil is more rigidly fixed to the housing than the magnet assembly, the vibrations of the coil make the housing vibrate. The vibrations are transmitted to the oval window of the ear through the ossicles.

DESCRIPTION OF THE INVENTION 5

 Aspects of the present invention are described in the independent claims.

  In one embodiment, the present invention comprises a floating mass transducer that can be implanted or mounted externally to produce vibrations in the vibratory structures of the ear. A floating mass transducer generally includes: a housing vibrationally coupled to a vibrating structure of an ear, and a mass mechanically coupled to the housing, where the mass vibrates in direct response to an externally generated electrical signal 10, whereby, the vibration of the mass causes the inertial vibration of the housing, producing vibrations in the vibratory structure of the ear.

 In one embodiment, the floating mass transducer includes a magnet disposed inside the housing. The magnet generates a magnetic field and is able to move inside the housing. A coil is also placed inside the housing but, unlike the magnet, the coil is not free to move inside the housing 15. When an alternating current is provided to the coil, the coil generates a magnetic field that interacts with the magnetic field of the magnet, causing the magnet and the coil / housing to vibrate relative to each other. The vibration of the housing translates into vibrations of the vibratory structure of the ear. The coil or coils are attached to an external surface of the housing.

  In one embodiment, the floating mass transducer is attached to the skull bone inside the middle ear. The floating mass transducer produces vibrations in the skull, which in turn produce vibrations in the cochlear fluid, resulting in auditory perception. The floating mass transducer can be attached to the bone with a screw or other fixation mechanism. Alternatively, the floating mass transducer can be incorporated into a piece of nozzle (for example, a piece of diving nozzle) that produces vibrations in the skull through the teeth.

  Additional aspects will be apparent from a detailed reading of the following description and the 25 attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

 Figure 1 is a schematic representation of a portion of the human auditory system.

 Figure 2a is a conceptual view of a floating mass transducer according to the present invention; Figure 2b shows the opposite vibration of a floating mass transducer, and Figures 2c and 2d illustrate the relative vibrations of the floating mass in different configurations.

 Figure 3 is a cross-sectional view of a floating mass transducer having a floating magnet.

 Figure 4 is a partial perspective view of a floating mass transducer having a floating magnet.

 Figure 5 is a schematic representation of a portion of the human auditory system showing a floating mass transducer connected to an anvil of the middle ear, and Figure 5b is a perspective view of the floating mass transducer of Figure 5a.

 Figures 6a-6f show embodiments of a floating mass transducer with a floating magnet mass according to the present invention. Figure 6g shows an example of a floating mass transducer.

 Figure 7a is a cross-sectional side view of a floating mass transducer having a floating magnet, and Figure 7b is a schematic representation of a portion of the auditory system showing the embodiment of Figure 7a placed around a portion of a stirrup of the middle ear.

 Figure 8 is a schematic representation of a portion of the auditory system showing a floating mass transducer and a total replacement ossicular prosthesis fixed inside the ear.

 Figure 9 is a schematic representation of a portion of the auditory system showing a floating mass transducer and a partial replacement ossicular prosthesis fixed inside the ear. Four. Five

 Figure 10 is a schematic representation of a portion of the auditory system showing a floating mass transducer positioned to receive the alternating current of a subcutaneous coil inductively coupled to an external sound transducer placed outside the head of a patient.

 Figure 11a is a cross-sectional view of a floating mass transducer having a floating coil, and Figure 11b is a side view of the floating mass transducer of Figure 11a. fifty

 Figure 12 is a cross-sectional view of a floating mass transducer having an angular momentum mass magnet.

 Figure 13 is a cross-sectional view of a floating mass transducer having a piezoelectric element.

 Fig. 14 is a schematic representation of a portion of the auditory system showing a floating mass transducer having a piezoelectric element positioned to receive the alternating current of a subcutaneous coil inductively coupled to an external sound transducer positioned outside the patient head

 Figure 15a is a cross-sectional view of a floating mass transducer having a thin membrane incorporating a piezoelectric band, and Figure 15b is a side view of the floating mass transducer of Figure 15a.

 Figure 16 is a cross-sectional view of a floating mass transducer having a piezoelectric battery.

 Figure 17 is a cross-sectional view of a transducer having a floating mass of two piezoelectric bands. fifteen

 Figure 18 is a schematic representation of a portion of the auditory system showing a floating mass transducer attached to the tympanic membrane to receive the alternating current of a pickup coil in the ear canal.

 Figure 19a is a schematic representation of a portion of the auditory system showing a floating mass transducer removably attached to the tympanic membrane to receive the alternating current of a pickup coil in the ear canal, and Figure 19b illustrates the position of a floating mass transducer in the tympanic membrane.

 Figure 20a is a perspective view of a flexible insert incorporating a floating mass transducer; Figure 20b is a cross-sectional view of the flexible insert, and Figure 20c is a schematic representation of a portion of the auditory system showing the flexible insert in the ear canal. 25

 Figure 21a is a schematic representation of a portion of the auditory system showing another implementation where a floating mass transducer is placed in contact with the tympanic membrane, and Figure 21b illustrates the position of a flexible floating mass transducer in the tympanic membrane. .

 Figure 22 is a schematic representation of a portion of the auditory system showing a cross-sectional view of the external sound transducer shell connector. 30

 Figure 23 is a schematic representation of a portion of the auditory system showing a floating mass transducer located in the oval window for receiving alternating current from a subcutaneous coil inductively coupled to an external sound transducer placed outside the head of a patient.

 Figure 24 is a schematic representation of a portion of the auditory system showing a fully internal hearing aid incorporating floating mass transducers. 35

 Figures 25a and 25b are schematic representations of a portion of the auditory system showing a floating mass transducer connected to the bone in the middle ear.

 Figure 26 shows a diving nozzle incorporating floating mass transducers to transmit sound by bone conduction.

 Figure 27 is an illustration of the system incorporating a Doppler laser speedometer (LDV) to measure the vibratory motion of the middle ear.

 Figure 28 represents, by a frequency and response curve, the vibration movement of the live human eardrum as a function of the frequency of the sound waves that have been supplied thereto.

 Figure 29 is a cross-sectional view of a transducer (transducer 4b) placed between the anvil and the hammer during corpse experimentation. Four. Five

 Figure 30 illustrates through a frequency and response curve that the use of transducer 4b resulted in an increase in the high frequency range above 2 kHz.

 Figure 31 illustrates through a frequency and response curve that the use of transducer 5 resulted in a noticeable improvement in frequencies between 1 and 3.5 kHz with a maximum power exceeding 120 dB equivalent SPL compared to a line of Stirrup vibration base when activated with sound. fifty

 Figure 32 illustrates through a frequency and response curve that the use of transducer 6 resulted in a noticeable improvement in frequencies above 1.5 kHz with a maximum power exceeding 120 dB equivalent SPL compared to a line of Stirrup vibration base when activated with sound.

DETAILED DESCRIPTION

INDEX 5

I. GENERAL

II. ELECTROMAGNETIC FLOATING MASS TRANSDUCER

A. Floating mass magnet

B. Floating mass coil

C. Angular momentum mass magnet 10

III. PIEZOELECTRIC FLOATING MASS TRANSDUCER

A. Cantilever

B. Thin membrane 15

C. Piezoelectric battery

D. Double piezoelectric bands

IV. EXTERNAL CONFIGURATION OF THE FLOATING MASS TRANSDUCER

 twenty

A. Trailer

B. Not coupled

C. Shell Connector

V. INTERNAL CONFIGURATION OF THE FLOATING MASS TRANSDUCER 25

A. Middle ear fixation without disarticulation

B. Total and partial replacement osicular prosthesis

C. Completely internal

D. Surgery 30

SAW. BONE DRIVING FLOATING MASS TRANSDUCER CONFIGURATION

A. Middle ear fixation

B. Nozzle part 35

VII. FLOATING MASK TRANSDUCER OF ZUMBID MASK

VIII. EXPERIMENTAL

 40

A. Examples of In Vivo corpses

B. In Vivo subjective evaluation of speech and music.

I. GENERAL

 Four. Five

 The present invention provides an improved transducer that can be implanted or mounted externally to transmit vibrations to the vibratory structure of the ear (as defined above). A "transducer" as used herein is a device that converts energy or information from one physical quantity to another physical quantity. For example, a microphone is a transducer that converts sound waves into electrical impulses.

 The transducer employed in the present invention is a floating mass transducer (FMT ™). A floating mass transducer 50 has a "floating mass" which is a mass that vibrates in direct response to an external signal that corresponds to the sound waves. The mass is mechanically coupled to a housing that can be mounted on a vibrating structure of the ear. Thus, the mechanical vibrations of the floating mass are transformed into a vibration of the vibratory structure, allowing the patient to hear. A floating mass transducer can also be used as a transducer to transform mechanical vibrations into electrical signals. 55

  To understand the present invention it is necessary to understand the theory on which the floating mass transducer is based - the principle of energy conservation. The principle of conservation of energy states that energy is not created or destroyed, but only changes from one form to another. More specifically, the mechanical energy of a system of bodies connected to each other is conserved (excluding friction). In such a system, if a body loses energy, a connected body gains energy. 60

  Figure 2a illustrates a conceptual view of a floating mass transducer. A floating block 2 (that is, the "floating mass") is shown connected to an opposite block 4 by a flexible connection 6. The flexible connection is an example of mechanical coupling that allows the vibrations of the floating block to be transmitted to the opposite block . In operation, a signal that corresponds to the sound waves causes the floating block to vibrate. As the floating block vibrates, the vibrations are carried through the flexible connection to the opposite block. The inertial vibration 5 resulting from the opposite block generally "counteracts" the vibration of the floating block. Figure 2b illustrates this opposite vibration of the blocks, where the double arrows represent the relative vibration of each block.

  The relative vibration of each of the blocks is, in general, inversely proportional to the inertia of the block. Therefore, the relative vibration of the blocks will be affected by the relative inertia of each block. The inertia of the block can be affected by the mass of the block or other factors (for example, if the block is attached to another structure). In this simple example, the inertia of a block will be presumed to be equal to its mass.

  Figure 2c shows the relative vibration of the blocks where the mass of the floating block 2 is greater than the mass of the opposite block 4. The double arrows indicate that the relative vibration of the floating block will be less than the relative vibration of the opposite block. In an embodiment that operates according to Figure 2c, a magnet comprises the floating block. The magnet is placed inside a housing such that it is free to vibrate in relation to the housing. A coil is fixed inside the housing to produce vibration of the magnet when an alternating current flows through the coil. Together, the housing and the coil comprise the opposite block and transmit a vibration to the vibratory structure. This embodiment will be described in more detail with reference to Figure 3.

  Figure 2d illustrates the relative vibration of the blocks, where the mass of the floating block 2 is less than the mass of the opposite block 4. The double arrows indicate that the relative vibration of the floating block will be greater than the relative vibration of the opposite block. In an embodiment that operates according to Figure 2d, a coil and a diaphragm together comprise the floating block. The diaphragm is a part of a housing and the coil is fixed to the diaphragm inside the housing. The coil is arranged inside a housing such that it is free to vibrate in relation to the housing. A magnet is fixed inside the housing, so that the coil 25 vibrates in relation to the magnet when an alternating current flows through the coil. Together, the housing and the magnet comprise the opposite block. However, in this embodiment it is the coil and the diaphragm (that is, the floating block) that transmit a vibration to the vibratory structure. This embodiment will be described in more detail with reference to Figures 11a and 11b.

  The above discussion is intended to present the basic theory of operation of the floating mass transducer 30 of the present invention. The floating mass transducer is vibrationally coupled to a vibrating structure of the ear. The floating mass transducer is vibrationally coupled to a vibratory structure, which means that the transducer is capable of transmitting vibrations to the vibratory structure. By way of example, the floating mass transducer can be mounted on the vibrating structure with a mounting mechanism, including glue, adhesive, velcro, sutures, suction, screws, springs, and the like. Therefore, the floating mass transducer can be attached to an ossicle in the middle ear by using a clip. In addition, the floating mass transducer can be mounted externally to produce vibrations in the tympanic membrane as when the floating mass transducer is fixed to the tympanic membrane by means of an adhesive. In addition, the floating mass transducer can be mounted or otherwise placed in vibratory contact with a non-vibrating structure, such as the skull or teeth. The following is a general discussion of a specific embodiment of a floating mass transducer. 40

  An embodiment of a floating mass transducer comprises a magnet assembly and a coil fixed inside a housing that will usually be sealed, in particular for implantable devices, where openings could increase the risk of infection. For implantable configurations, the housing can be provided to be fixed to an ossicle in the middle ear. Although the invention is not limited by the shape of the housing, it is preferred that the housing is in the form of a cylindrical capsule. Similarly, it is not intended that the invention be limited by the composition of the housing. In general, it is preferred that the housing be composed, and / or coated, of a biocompatible material.

  The housing contains the coil and magnet assembly. Typically, the magnet assembly is positioned such that it can oscillate freely without colliding with the coil or inside the housing itself. When properly placed, a permanent magnet inside the assembly produces a predominantly uniform field flow. Although this embodiment involves the use of permanent magnets, electromagnets can also be used.

  Several components are involved in the supply of the signal derived from the sound generated externally to the coil placed inside the middle ear housing. First, an external sound transducer similar to a conventional hearing aid transducer is placed on the skin or skull. This external transducer processes the sound and transmits a signal, by magnetic induction, to a subcutaneous coil transducer. From a coil located in the subcutaneous transducer, alternating current is conducted by a pair of wires to the transducer coil implanted in the middle ear. That coil is placed more rigidly on the inner wall of the housing than the magnet also placed therein.

  When alternating current is supplied to the middle ear housing, attractive and repulsive forces are generated by the interaction between the magnet and the coil. As the coil is more rigidly attached to the housing than the magnet assembly, the coil and housing move as a unit as a result of the forces produced. The vibrating transducer activates the highest quality sound perception when the relationship between the displacement of the housing and the coil current is substantially linear. This linearity is best achieved by placing and maintaining the coil in the substantially uniform flow field produced by the magnet assembly.

  In order for the transducer to function effectively, it must vibrate the ossicles with sufficient force to transfer the vibrations to the cochlear fluid in the inner ear. The force of the vibrations created by the transducer can be optimized by maximizing the mass of the magnet assembly in relation to the combined mass of the coil and the housing, and the energy product (PE) of the permanent magnet.

  Floating mass transducers according to the present invention can be mounted on any of the vibrating structures of the ear. Preferably, the transducer is fixed or arranged in these positions so that the transducer is prevented from coming into contact with bone or tissue, which would absorb the mechanical energy it produces. When the transducer is attached to the ossicles chain, a biocompatible clip can be used. However, in an alternative transducer design, the housing contains an opening that results in it being annular, which allows the housing to be placed around the stirrup or anvil. In other implementations, the transducer is fixed to partial or total ossicular replacement prostheses. In other implementations, the transducer is used in an external auditory device or attached to a non-vibratory structure, such as the skull.

II. FLOATING MASS ELECTROMAGNETIC TRANSDUCER 20

 It is known that a magnet generates a magnetic field. A coil that has a current flowing through it also generates a magnetic field. When the magnet is placed very close to the coil and an alternating current flows through the coil, the interaction of the respective magnetic fields causes the magnet and the coil to vibrate with each other. This property of the magnetic fields of the magnets and of the coils provides the basis for floating mass transducers as follows. 25

A. Floating mass magnet

 The structure of an embodiment of a floating mass transducer is shown in Figures 3 and 4. In this embodiment, the floating mass is a magnet. The transducer 100 generally comprises a sealed housing 10 having a magnet assembly 12 and a coil 14 disposed therein. The magnet assembly is freely suspended inside the housing, and the coil is rigidly fixed to the housing. As described, the 30 magnet assembly 12 preferably includes a permanent magnet 42 and associated pole pieces 44 and 46. When the alternating current is conducted to the coil, the coil and magnet assembly oscillate with respect to each other and make Let the accommodation vibrate. The housing 10 is provided to be fixed in the middle ear, which includes the hammer, anvil and stirrup, collectively known as ossicles, and the region surrounding the ossicles. The example housing is preferably a cylindrical capsule with a diameter of 1 mm and a thickness of 1 mm, and is made of a biocompatible material such as titanium. The housing has a first and second faces 32, 34 that are substantially parallel to each other and an outer wall 23, which is substantially perpendicular to the faces 32, 34. Fixed inside the housing is an inner wall 22 defining a circular region and extending substantially parallel to the outer wall 23.

  Air spaces 30 surround the magnet assembly to separate it from the interior of the housing and so that it can swing freely without colliding with the coil or housing. The magnet assembly is connected to the interior of the housing by flexible membranes, such as silicone buttons 20. The magnet assembly can alternatively float in a jelly-like medium, such as silicon gel, which fills the air spaces in the housing. A substantially uniform flow field is produced by configuring the magnet assembly as shown in Figure 3. The assembly includes a permanent magnet 42 placed with the ends 48, 50 containing the north and south poles substantially parallel to the circular faces 34, 32 of the housing. A first cylindrical pole piece 44 is connected to the end 48 containing the south pole of the magnet and a second pole piece 46 is connected to the end 50 containing the north pole. The first pole piece 44 is oriented with its circular faces substantially parallel to the circular faces 32, 34 of the housing 10. The second pole piece 46 has a circular face that has a rectangular cross section and is substantially parallel to the circular faces 32 , 34 of 50 accommodation. The second pole piece 46 also has a pair of walls 54 that are parallel to the wall 23 of the housing and that surround the first pole piece 44 and the permanent magnet 42.

  The pole pieces must be made of a magnetic material such as ferrite or SmCo. They provide a path for the magnetic flux of the permanent magnet 42, which is less resistant than the air surrounding the permanent magnet 42. The pole pieces conduct most of the magnetic flux and, therefore, make it pass from the second pole piece 46 to the first pole piece 44 in the space in which the coil 14 is placed.

  For the device to function properly, it must vibrate a vibrating structure with enough force for vibrations to be perceived as sound waves. Vibration strength is maximized

better by optimizing two parameters: the mass of the magnet assembly in relation to the combined mass of the coil and the housing, and the energy product (PE) of the permanent magnet 42.

  The relationship between the mass of the magnet assembly and the combined mass of the magnet assembly, the coil and the housing is easier to optimize by constructing the housing of a thin machined lightweight material, such as titanium and by configuring the assembly of magnet to fill a large part of the interior space of the housing, although there must be a suitable separation between the magnet assembly and the housing and the coil for the magnet assembly to vibrate freely inside the housing.

  The magnet should preferably have a high energy product. NdFeB magnets that have forty-five energy products and SmCo magnets that have thirty-two energy products are currently available. A high energy product maximizes the attraction and repulsion between the magnetic fields of the coil 10 and the magnet assembly and, therefore, maximizes the force of the transducer oscillations. Although it is preferable to use permanent magnets, electromagnets can also be used in the embodiment of the present invention.

  The coil 14 partially surrounds the magnet assembly 12 and is fixed to the inner wall 22 of the housing 10 such that the coil is fixed more rigidly to the housing than the magnet assembly. Air spaces separate the coil from the magnet assembly. In an implementation where the transducer is implanted, a pair of wires 24 are connected to the coil and pass through an opening 26 in the housing towards the outside of the transducer, through the channel surgically created in the temporal bone (indicated as CT in Figure 10), and attached to a subcutaneous coil 28. Subcutaneous coil 28, which is preferably implanted under the skin behind the ear, supplies alternating current to coil 14 through wires 24. The opening 26 is closed around wires 24 to form a seal (not shown) that prevents contaminants from entering the transducer. twenty

  The perception of the sound that the vibratory transducer ultimately activates is of the highest quality when the relationship between the displacement of the housing 10 and the current in the coil 14 is substantially linear. For the relationship to be linear, there must be a corresponding displacement of the housing for each current value reached by the alternating current in the coil. The linearity is as closely as possible by placing and maintaining the coil in the substantially uniform flow field 16 produced by the magnet assembly 25.

  When the magnet assembly, the coil, and the housing are configured as in Figure 3, the alternating current in the coil causes the housing to swing from side to side in the directions indicated by the double arrow of Figure 3. Figure 4 is a partial perspective view of the transducer of Figure 3. The transducer is more efficient when placed in such a way that the movement from side to side of the housing produces movement 30 from side to side of the oval window EE, such as It is indicated by the double arrow in Figure 5a.

  The transducer can be fixed in different structures inside the ear. Figure 5 shows a transducer 100 connected to an anvil MM by means of a biocompatible clip 18 that is fixed on one of the circular faces 32 of the housing 10, and that at least partially surrounds the anvil MM. Clip 18 firmly holds the transducer to the anvil, so that the vibrations of the housing that are generated during operation are conducted along the bones of the middle ear to the oval window EE of the inner ear, and ultimately to the fluid cochlear as described above. An example clip 18, shown in Figure 5b, includes two pairs of titanium tips 52 that have a substantially arched shape and that can be pressed tightly around the anvil.

  The transducer 100 can be connected to any of the vibrating structures of the ear. The transducer must be mechanically isolated from bone and tissue in the surrounding region, since these structures will tend to absorb the mechanical energy produced by the transducer. For the purposes of this description, the surrounding region consists of all structures in and around the outer, middle and inner ear that are not the vibrating structures of the ear.

  Figures 6a-6f show some preferred embodiments of the floating mass transducer according to the present invention incorporating a floating mass magnet. In Fig. 6a, the floating mass transducer 100 has a cylindrical housing 110. The housing has a pair of notches on the outer surface to retain or fix a pair of 45 coils 112. The coils can be of various metallic materials, such as Gold and platinum The housing retains the bobbins just as a bobbin retains the thread. The housing includes a pair of end plates 114 that seal the housing. The housing can be constructed of materials such as titanium, iron, stainless steel, aluminum, nylon, and platinum. In one embodiment, the housing is constructed of titanium and the end plates are laser welded to seal the housing. fifty

  Inside the housing there is a cylindrical magnet 116 which can be a SmCo magnet. The magnet is not rigidly fixed inside the housing. Instead, a pressure mechanism supports, and can in fact suspend, the magnet inside the housing. As can be seen, the pressure mechanism is a pair of soft silicone pads 118 that are at each end of the magnet. Thus, the magnet is generally free to move between the end plates subject to the retention provided by the silicone pads inside the housing. Although silicone pads are shown, other pressure mechanisms such as springs and magnets can be used.

  When an electrical signal corresponding to ambient sound passes through the coils 112, the magnetic field generated by the coils interacts with the magnetic field of the magnet 116. The interaction of the magnetic fields causes the magnet to vibrate inside the housing. Preferably, the windings of the two coils are wound in opposite directions to achieve a good resulting force on the magnet (ie, the axial forces of each coil do not cancel each other out). The magnet vibrates inside the housing and is pressed by the 5-pressure mechanism inside the housing. The resonance frequency of the floating mass transducer can be determined by the "firmness" by which the pressure mechanism presses the magnet. For example, if a higher resonance frequency of the floating mass transducer is desired, springs with a relatively high elastic force can be used as a pressure mechanism. Alternatively, if a lower resonance frequency of the floating mass transducer is desired, springs with a relatively low elastic force can be used as a pressure mechanism 10.

  It is known that an electromagnetic field in the vicinity of a metal induces a current in the metal. This current can oppose or interfere with magnetic fields. Despite a thin metal layer, such as titanium, separates the coils 112 and the magnet 116, if the metal layer is thin enough (for example, 0.05 mm), then the electromagnetic interference is negligible. In addition, the housing may be composed of a non-conductive material such as nylon. In order to reduce friction inside the housing, the internal surface of the housing and / or the magnet can also be coated to reduce the coefficient of friction.

  Figure 6b shows the magnetic field produced by the magnet in the floating mass transducer of Figure 6a. As shown, the magnetic field lines pass through the coils 112. The efficiency of the floating mass transducer is increased by placing the coils in a position such that the magnetic flux through the coils is maximized. Thus, the coils are preferably placed near the poles of the magnet 116.

  Although the friction-opposing movement of the magnet inside the housing can be reduced by coating the internal surface of the housing and / or the magnet, Figure 6b shows an embodiment of a floating mass transducer having a friction reduction in the Inside the accommodation The floating mass transducer is generally the same, as shown in Figure 6a, except that the floating mass transducer has a spherical magnet 25 122 inside the housing. A spherical magnet can reduce the amount of low frequency distortion caused by an edge of the cylindrical magnet that captures the inner surface of the housing.

  The spherical magnet can reduce friction inside the housing in two ways. First, the spherical magnet has less surface area in contact with the inner surface of the housing and has no edges. Secondly, the spherical magnet can roll inside the housing, which produces less friction than friction by sliding. Thus, the spherical magnet can reduce friction inside the housing with the opposing movement of the magnet.

  The floating mass transducer of Figure 6c is shown with a clip attached to one end of the housing. The clip can be a metal clip welded to the housing to allow the transducer to be fixed to an ossicle. Other fixing mechanisms can also be used. 35

  Figure 6d shows the magnetic field produced by the magnet in the floating mass transducer of Figure 6a. As shown, the magnetic field lines pass through the coils 112 in a manner similar to Figure 6b. The efficiency of the floating mass transducer is increased by placing the coils in a position such that the magnetic flux through the coils is maximized. Thus, the coils are preferably placed near the poles of the magnet 122. 40

  Figure 6e shows another embodiment of a floating mass transducer with a floating mass magnet. The transducer 100 has a cylindrical housing 130 with an open end. The housing has a pair of notches on the outer surface to retain a pair of coils 132. The coils can be of various metallic materials such as gold and platinum. The housing retains the bobbins just as a bobbin retains a thread. The housing includes an end plate 134 that seals the housing. The housing can be constructed of 45 materials such as titanium, iron, stainless steel, aluminum, nylon, and platinum. In one embodiment, the housing is constructed of titanium and the end plate is laser welded to seal the housing.

  Inside the housing there is a cylindrical magnet 136 which can be a SmCo magnet. The magnet is not rigidly fixed inside the housing. On each side of the magnet there is a pressure mechanism. As can be seen, the pressure mechanism is a pair of magnets 138 placed inside the housing, so that the equal poles between magnets 136 and 138 are adjacent to each other. Thus, the magnet is generally free to move between the magnets 138 except for the opposition provided by the magnet 136 that presses the magnets.

  When an electrical signal corresponding to ambient sound passes through the coils 112, the magnetic field generated by the coils interacts with the magnetic field of the magnet 136. The interaction of the magnetic fields causes the magnet to vibrate inside the housing. The magnet vibrates inside the housing and is pressed by the pressure mechanism inside the housing. The resonance frequency of the floating mass transducer can be determined by the "firmness" with which the pressure mechanism presses the magnet. For example, if a higher resonance frequency of the floating mass transducer is desired, magnets 138 may

placed in the vicinity of magnet 136. Alternatively, if a lower resonance frequency of the floating mass transducer is desired, magnets 138 may be placed further away from magnet 136.

  The transducer can be manufactured by placing a magnet inside the housing, pressing the magnet inside the housing, sealing the housing, and wrapping at least one coil around the outer surface of the housing. The pressure of the magnet inside the housing may include the placement of 5 silicone pads, springs, magnets, or other types of pressure mechanisms inside the housing. In addition, at least the coil can be fixed to an internal surface of the housing. In a preferred embodiment, the housing is hermetically sealed.

 Transducer 100 is shown coated with a coating 140. The coating can be acrylic or a polyimide. In addition, the transducer can be coated with a resorbable coating that reduces damage to the device resulting from handling during implantation. A resorbable polymer can be used, so that the coating will dissolve. Thus, after the coating is absorbed, the coating does not add mass to the floating mass transducer.

  Figure 6f shows a floating mass transducer that is the same as the transducer shown in Figure 6a except for the polar pieces of the tubular magnet 150 and 152. The efficiency of the floating mass transducer can be increased by increasing the magnetic flux through the coils 112. The polar pieces added to the ends of the magnet 116 can further help redirect the magnetic field lines through the coils, which increases the magnetic flux through the coils. The polar pieces can be made of a metallic material.

  Alternatively, or in addition to the polar pieces, the tubular magnet 152 can be placed around the housing, as shown. The poles of the magnet 152 are opposite the poles of the magnet 116 to direct more lines 20 of magnetic field through the coils, which increases the magnetic flux through the coils. The tubular magnet can be of a fine magnetized metallic material.

  As shown in Figure 6f, the pressure mechanism may be integrated in the end plates 114. Silicone pads 118 are placed or fixed in notches in the end plates.

  Figure 6g shows an example of a floating mass transducer with a floating mass magnet. The transducer 100 has a cylindrical housing 160 with an open end. The housing includes an end plate 162 that seals the housing when pressed with an interference fit at the open end of the housing. A washer 164 helps seal the housing. In one embodiment, the housing, washer and end plate are gold plated, so that the housing is sealed with gold-gold contacts and without being welded.

  A pair of coils 166 are fixed to an internal surface of the housing. A floating cylindrical magnet 30 is also placed inside the housing. The magnet is not rigidly fixed inside the housing. On each side of the magnet there is a pressure mechanism. As shown, the pressure mechanism is a pair of springs 170. Thus, the magnet is generally free to move from side to side except for the pressure springs. Cables 24 may extend through end plate 162, as shown.

  An alternative transducer 100a having an alternative mechanism for attaching the transducer to structures 35 within the ear is shown in Figures 7a and 7b. In this alternative transducer 100a, the housing 10a has an opening 36 that passes from the first face 32a to the second face 34a of the housing, and thus is annularly shaped. When implanted, a portion of the stirrup HH is placed inside the opening 36. This is achieved by separating the stirrup HH from the anvil MM and sliding the O-shaped transducer around the stirrup HH. The separated ossicles then return to their natural position and where the connective tissue between them heals and causes them to reconnect. This example can be set around the anvil in a similar manner.

  Figures 8 and 9 illustrate the use of the transducer of the present invention in combination with a total ossicular replacement prosthesis and a partial ossicular replacement prosthesis. These illustrations are merely representative; Other designs that incorporate the transducer into the ossicular replacement prosthesis can be easily designed. Four. Five

  Osicular replacement prostheses are constructed with biocompatible materials such as titanium. Often, during ossicular reconstruction surgery, ossicular replacement prostheses are formed in the operating room, as necessary to carry out the reconstruction. As shown in Figure 8, a total ossicle replacement prosthesis may comprise a pair of elements 38, 40 connected to the circular faces 32b, 34b of the transducer 100. The prosthesis is placed between the tympanic membrane CC and the oval window EE, and is preferably of sufficient length to hold in friction position. With reference to Figure 9, a partial replacement ossicular prosthesis may comprise a pair of elements 38c, 40c connected with the circular faces 32c, 34c of the transducer and be placed between the anvil MM and the oval window EE.

  Figure 10 shows a schematic representation of a transducer 100 and related components placed inside the skull of a PP patient. An external sound transducer 200 is substantially identical in design to a conventional hearing aid transducer, and comprises a microphone, a processing unit of

Sound, an amplifier, a battery, and an external coil, none of which is shown in detail. The external sound transducer 200 is placed outside the PP skull. A subcutaneous coil transducer 28 is connected to wires 24 of transducer 100 and is typically placed below the skin behind the ear, such that the outer coil is placed directly over the placement of subcutaneous coil 28.

  The sound waves are converted into an electrical signal by means of the microphone and the sound processor of the external sound transducer 200. The amplifier increases the signal and sends it to the external coil, which subsequently supplies the signal to the subcutaneous coil 28 by induction. magnetic The cables 24 conduct the signal to the transducer 100 through a surgically created TC channel in the temporal bone. When the alternating current signal representing the sound wave is supplied to the coil 14 in the implantable transducer 100, the magnetic field produced by the coil interacts with the magnetic field of the magnet assembly 12. 10

  When the current alternates, the magnet assembly and the coil alternately attract and repel each other. The alternating forces of attraction and repulsion cause the magnet and coil assembly to move alternately closer and further apart. As the coil is more rigidly attached to the housing than the magnet assembly, the coil and housing move together as a single unit. The directions of the reciprocating movement of the housing are indicated by the double arrow in Figure 10. The vibrations are conducted through the stirrup HH to the oval window EE and, finally, to the cochlear fluid.

B. Floating mass coil

 The structure of another example of a floating mass transducer is shown in Figures 11a and 11b. Unlike the previous embodiment, the floating mass in this embodiment is the coil. The transducer 100 generally comprises a housing 202 having a magnet assembly 204 and a coil 206 disposed therein. The housing is generally a cylindrical capsule with an open end that is sealed by a flexible diaphragm 208. The magnet assembly may include a permanent magnet and associated polar pieces to produce a substantially uniform flow field, as described above with reference to figure 3. The magnet assembly is fixed to the housing, and the coil is fixed to flexible diaphragm 208. The diaphragm is shown with a clip 210 fixed to the center of the diaphragm, which allows the transducer to be fixed to the anvil MM, as shown in figure 5a. 25

  The coil is electrically connected to an external power source (not shown) that provides alternating current to the coil through wires 24. When alternating current is conducted to the coil, the coil and magnet assembly oscillate with each other, making Let the membrane vibrate. Preferably, the relative vibration of the coil and diaphragm is substantially greater than the vibration of the magnet assembly and the housing.

  For the device to function properly, it must vibrate a vibrating structure with sufficient force for vibrations to be perceived as sound waves. The force of the vibrations is best maximized by optimizing two parameters: the combined mass of the magnet assembly and the housing in relation to the combined mass of the coil and the diaphragm, and the energy product (PE) of the magnet.

  The ratio of the combined mass of the magnet assembly and the housing with respect to the combined mass of the coil and the diaphragm is more easily optimized by building the diaphragm of a lightweight flexible material, such as mylar. The housing must be of a biocompatible material such as titanium. The magnet should preferably have a high energy product. A high energy product maximizes attraction and repulsion between the magnetic fields of the magnet assembly and the coil and, therefore, maximizes the force of the oscillations produced by the transducer. Although it is preferable to use permanent magnets, electromagnets can also be used in the embodiment of the present invention. 40

C. Angular momentum mass magnet

 The structure of an example of a floating mass transducer is shown in Figure 12. In this example, the mass swings like a pendulum through an arc. The transducer 100 generally comprises a housing 240 having a magnet 242 and coils 244 disposed therein. The housing is generally a sealed rectangular capsule. The magnet is fixed to the housing, which is rotatably attached to a support 246. The support is fixed at the inside of the housing and allows the magnet to swing around an axis inside the housing. Coils 244 are fixed inside the housing.

  The coils are electrically connected to an external power supply (not shown) that provides alternating current to the coils through some wires 24. When current is conducted to the coils, a coil creates a magnetic field that attracts the magnet 242, while that the other coil creates a magnetic field that repels magnet 242. An alternating current will cause the magnet to vibrate with respect to the coil and the housing. A clip 248 is shown that can be used to connect the housing to an ossicle. Preferably, the relative vibration of the coils and the housing is substantially greater than the vibration of the magnet.

  For the device to function properly, it must vibrate a vibrating structure with enough force for vibrations to be perceived as sound waves. The force of the vibrations is maximized 55

better by optimizing two parameters: the mass of the magnet with respect to the combined mass of the coils and the housing, and the energy product (PE) of the magnet.

  The relationship between the mass of the magnet and the combined mass of the coils and the housing is easier to optimize by constructing the housing of a thin and light machined material, such as titanium and configuring the magnet to fill a large part of the interior space of the housing, although there must be a proper separation between the magnet and the coil for the magnet to swing or vibrate freely inside the housing.

  The magnet should preferably have a high energy product. A high energy product maximizes attraction and repulsion between the magnetic fields of magnets and coils and, therefore, maximizes the force of transducer oscillations. Although it is preferable to use permanent magnets, electromagnets can also be used. 10

III. PIEZOELECTRIC FLOATING MASS TRANSDUCER

 Piezoelectric electricity results in the application of mechanical pressure on a dielectric crystal. On the contrary, an application of a voltage between certain faces of a dielectric crystal produces a mechanical deformation of the crystal. This reciprocal relationship is called the piezoelectric effect. Piezoelectric materials include quartz, polyvinylidene fluoride (PVDF), lead titanate zirconate (Pb [ZrTi] O3), and the like. A piezoelectric material can also be formed as a bimorph that is formed by joining together piezoelectric layers with different polarities. When a voltage of one polarity is applied to a bimorphic layer and a voltage of polarity opposite to the other bimorphic layer is applied, one layer contracts, while the other layer expands. Therefore, the bimorph bends towards the contraction layer. If the polarities of the voltages are reversed, the bimorph bends in the opposite direction. The properties of the bimorph piezoelectric and piezoelectric provide the basis for floating mass transducers as follows.

A. Cantilever

 The structure of a piezoelectric floating mass transducer is shown in Figure 13. In this example, the floating mass is vibrated by a piezoelectric bimorph. A transducer 100 generally comprises a housing 302 having a bimorph assembly 304 and a drive weight 306 disposed therein. The housing is generally a sealed rectangular capsule. One end of the bimorph assembly 304 is fixed to the interior of the housing and is composed of a short piezoelectric band 308 and a longer piezoelectric band 310. The two bands are oriented so that one band contracts while the other band expands when applied a tension across the bands through the wires 24.

  The drive weight 306 is fixed to one end of the piezoelectric band 310 (the "overhang"). When alternating current is conducted to the bimorph assembly, the housing and the drive weight oscillate with respect to each other causing the housing to vibrate. Preferably, the relative vibration of the housing is substantially greater than the vibration of the drive weight. A clip can be attached to the housing, which allows the transducer to be attached to the anvil MM, as shown in Figure 5a.

  For the device to function properly, it must vibrate a vibrating structure with sufficient force for vibrations to be perceived in the form of sound waves. The force of the vibrations is best maximized by optimizing two parameters: the mass of the drive weight in relation to the mass of the housing, and the efficiency of the piezoelectric bimorph assembly.

 The relationship between the mass of the drive weight and the mass of the housing is easier to optimize by constructing the housing of a thin and light machined material, such as titanium, and setting the drive weight to cover a large part of the interior space of the housing, although there must be adequate separation between the drive weight and the housing so that the housing does not come into contact with the drive weight when it vibrates.

  In another example, the piezoelectric bimorph assembly and the drive mass are inside a housing. Although the floating mass is vibrated by a piezoelectric bimorph, the bimorph assembly is fixed directly to an ossicle (for example, the anvil MM) with a clip, as shown in Figure 14. A transducer 100b has a bimorph assembly 304 composed of a short piezoelectric band 306 and a longer piezoelectric band 308. As before, the two bands are oriented such that one band contracts while the other band expands when a voltage is applied across the bands across of the cables 24. One end of the bimorph assembly is fixed on a clip 314 shown attached to the anvil. A drive weight 312 is fixed to the end of the piezoelectric band 308 opposite the clip in a position that does not make contact with the surrounding ossicles or tissue. Preferably, the mass of the drive weight is chosen so that all or a substantial part of the vibrations created by the transducer are transmitted to the anvil.

  Although bimorphic piezoelectric bands have been shown that with a long portion and a short portion, the entire cantilever may be composed of bimorphic piezoelectric bands of equal lengths. 55

B. Fine membrane

 The structure of another example of a floating mass transducer is shown in the figures. 15a and 15b. The floating mass is vibrated by a piezoelectric bimorph in association with a thin membrane. The transducer 100 comprises a housing 320 which is generally a cylindrical capsule with an open end that is sealed by a flexible diaphragm 322. A bimorph assembly 324 is placed inside the housing and fixed to the flexible diaphragm. The bimorph assembly includes two piezoelectric bands 326 and 328. The two bands are oriented so that one band contracts while the other band expands when a voltage is applied across the bands through the wires 24. The diaphragm is shown with a clip 330 fixed to the center of the diaphragm that allows the transducer to be fixed to an ossicle.

  When alternating current is conducted to the bimorph assembly, the diaphragm vibrates. Preferably, the relative vibration 10 of the bimorph assembly and the diaphragm is substantially greater than the vibration of the housing. For the device to function properly, it must vibrate a vibrating structure with enough force for vibrations to be perceived as sound waves. The force of the vibrations is best maximized by optimizing two parameters: the mass of the housing in relation to the combined mass of the bimorph assembly and the diaphragm. fifteen

  The relationship between the mass of the housing and the combined mass of the bimorph assembly and the diaphragm is easier to optimize by fixing a weight 332 inside the housing. The housing may be composed of a biocompatible material such as titanium.

C. Piezoelectric battery

 The structure of a piezoelectric floating mass transducer is shown in Figure 16. In this example, the floating mass is vibrated by a stack of piezoelectric bands. A transducer 100 generally comprises a housing 340 that has a piezoelectric battery 342 and a drive weight 344 disposed therein. The housing is generally a sealed rectangular capsule.

  The piezoelectric battery comprises multiple piezoelectric sheets. One end of the piezoelectric cell 340 is fixed inside the housing. The drive weight 344 is set at the other end of the piezoelectric cell. 25 When a voltage is applied across the piezoelectric bands through the cables 24, the individual piezoelectric bands expand or contract depending on the polarity of the voltage. As the piezoelectric bands expand or contract, the piezoelectric battery vibrates along the double arrow in Figure 16.

  When alternating current is conducted in the piezo battery, the drive weight vibrates causing the housing to vibrate. Preferably, the relative vibration of the housing is substantially greater than the vibration of the drive weight. A clip 346 can be fixed in the housing to allow the transducer to be attached to an ossicle.

  For the device to function properly, it must vibrate a vibrating structure with enough force for vibrations to be perceived as sound waves. Vibration strength is best maximized by optimizing two parameters: the mass of the drive weight in relation to the mass of the housing, and the efficiency of the piezoelectric bands.

  The relationship between the mass of the drive weight and the mass of the housing is easier to optimize by constructing the housing of a thin and light machined material, such as titanium and configuring the drive weight to fill a large part of the interior space of the housing, although there must be adequate separation between the drive weight and the housing so that the housing does not come into contact with the weight of the drive when it vibrates.

D. Double piezoelectric bands

 The structure of a piezoelectric floating mass transducer is shown in Figure 17. In this example, the floating mass is vibrated by a double piezoelectric band. A transducer 100 generally comprises a housing 360 with piezo bands 362 and a drive weight 364 disposed therein. Housing 45 is generally a sealed rectangular capsule.

  One end of each of the piezoelectric bands is fixed inside the housing. The drive weight 364 is set at the other end of each of the piezoelectric bands. When a voltage is applied across the piezoelectric bands through the cables 24, the piezoelectric bands expand or contract depending on the polarity of the voltage. As the piezoelectric bands expand or contract, the weight of the drive vibrates along the double arrow in Figure 17.

  When alternating current is conducted to the piezoelectric bands, the drive weight vibrates causing the housing to vibrate. Preferably, the relative vibration of the housing is substantially greater than the vibration of the drive weight. A clip 366 can be attached to the housing to allow the transducer to be fixed to an ossicle. 55

  For the device to function properly, it must vibrate a vibrating structure with enough force for vibrations to be perceived as sound waves. The force of the vibrations is best maximized by optimizing two parameters: the mass of the drive weight in relation to the mass of the housing, and the efficiency of the piezoelectric bands.

  The relationship between the mass of the drive weight and the mass of the housing is easier to optimize 5 by constructing the housing of a thin and light machined material, such as titanium and configuring the drive weight to fill a large part of the interior space of the housing, although there must be a proper separation between the drive weight and the housing so that the housing does not come into contact with the drive weight when it vibrates.

  This example has been described as having two piezoelectric bands. However, more than two piezoelectric bands can also be used.

IV. EXTERNAL FLOATING MASS TRANSDUCER CONFIGURATION

A. Trailer

 A floating mass transducer according to the present invention can also be attached to the eardrum membrane in the outer ear. Figure 18 illustrates a floating mass transducer attached to the tympanic membrane. A transducer 100 is shown attached to the hammer LL through the tympanic membrane CC with a clip 402. The transducer can also be fixed to the tympanic membrane by other methods, including screws, sutures, etc. The transducer receives the alternating current through the cables 24 that extend along the ear canal with a pickup coil 404.

  An external sound transducer 406 is placed behind the QQ shell. The external sound transducer is substantially identical in design to a conventional hearing aid transducer, and comprises a microphone, a sound processing unit, an amplifier and a battery, none of which are shown in detail. The sound waves are converted into an electrical signal using the microphone and the sound processor of the external sound transducer. The amplifier increases the signal and sends it through the wires 408 to a conductive coil 410. The wires 408 pass from the back of the shell to the front of the shell through a hole 412. The wires 25 can also be placed through the shell or any of a series of other paths. The conductive coil is adjacent to the collection coil, so there are actually two coils inside the ear canal.

  The conductive coil provides the signal to the pickup coil 404 by magnetic induction. The pickup coil produces an alternating current signal in the cables 24, whose floating mass transducer translates it into a vibration in the middle ear, as described above. Although this implementation has been described as drive and collection coils, it can also be implemented with a direct cable connection between the external sound transducer and the floating mass transducer.

  An obvious advantage of this implementation is that surgery in the middle ear is not necessary to implant the transducer. Therefore, the patient can have the transducer attached to an ossicle without the invasive surgery necessary to place the transducer in the middle ear. 35

B. Not coupled

 A floating mass transducer according to the present invention can be removably attached (ie, not coupled) to the tympanic membrane in the outer ear. The following paragraphs describe different implementations where the floating mass transducer is removably attached to the tympanic membrane.

  Figure 19a illustrates an implementation where the floating mass transducer of the present invention is removably placed in contact with the tympanic membrane. A transducer 100 is shown attached to the tympanic membrane CC with a flexible membrane 502. The flexible membrane may be composed of silicone and holds the transducer in contact with the tympanic membrane through a suction action, an adhesive, and the like. The transducer receives the alternating current through the cables 24 that extend along the ear canal with a pickup coil 504. The transducer, the wires and the pickup coil can be made to be disposable.

  An external sound transducer 506 is placed behind the QQ shell. The external sound transducer is substantially identical in design to a conventional hearing aid transducer, and comprises a microphone, a sound processing unit, an amplifier, a battery, and a conductive coil, none of which is shown in detail. The sound waves are converted into an electrical signal using the microphone and sound processor of the external sound transducer. The microphone can include a 508 tube that allows you to receive better sound from in front of the shell. The amplifier increases the signal and sends it to the conductive coil in the external sound transducer.

  The conductive coil provides the signal to the pickup coil 504 by magnetic induction. The pickup coil produces an alternating current signal in the cables 24, whose floating mass transducer translates 55

in a vibration in the middle ear, as described above. Although this implementation has been described as having drive and pickup coils, it can also be implemented with a direct cable connection between the external sound transducer and the floating mass transducer.

  Figure 19b illustrates the position of the floating mass transducer in the tympanic membrane. Transducer 100 and flexible membrane 502 are placed in the annular ring RR. Preferably, the transducer is placed near the 5 umbo region TT.

  Figure 20a shows a flexible insert that is used in another implementation where the floating mass transducer of the present invention is removably placed in contact with the tympanic membrane. A flexible insert 600 is mainly composed of a collection coil 602, cables 24, and a floating mass transducer 610. The collection coil 602 is preferably coated with a soft and flexible material, such as polyvinyl or silicone. The pickup coil is connected to the cables 24, which are flexible and can have a characteristic wavy pattern to release tension to provide durability to the cables by reducing the damaging effects of vibrations. The cables provide alternating current from the pickup coil to transducer 100, which is placed in contact with the umbo region of the tympanic membrane. Preferably, the transducer has a soft coating 606 (eg, silicone) on the side that will be in contact with the tympanic membrane. Figure 20b illustrates a side view of the flexible insert 600. The flexible insert can also be designed with more than two flexible cables supporting the transducer.

  Figure 20c illustrates the position of the flexible insert in the ear canal. The flexible insert 600 is placed deep within the ear canal so that the floating mass transducer is in contact with the tympanic membrane. The pickup coil can be driven by magnetic induction by an external sound transducer 20 608 comprising a microphone, a sound processing unit, an amplifier, a battery, and a conductive coil, none of which are described in detail. Although the external sound transducer is shown in the ear canal, it can also be placed in other places, including behind the shell. In addition, the external sound transducer can be made in the form of a collar. The conductive coil surrounds the patient's neck and produces a magnetic field that activates the collection coil by magnetic induction. 25

  Figure 21a illustrates another implementation where the floating mass transducer of the present invention is removably placed in contact with the tympanic membrane. A transducer 100 is shown attached to the tympanic membrane CC with a flexible membrane 702. The flexible membrane may be composed of silicone and keeps the transducer in contact with the tympanic membrane through a suction action or an adhesive. The transducer receives the alternating current through the wires 24 that extend through the flexible membrane to a collection coil 704. The collection coil can be placed inside the flexible membrane and activated by a conductive coil (not shown ) as described above.

  Figure 21b illustrates the position of the floating mass transducer of Figure 21a on the tympanic membrane. Transducer 100 and flexible membrane 702 are placed in the tympanic membrane CC. Preferably, the transducer is placed near the umbo region TT. A demodulator circuit 706 can be placed within the flexible membrane between the pickup coil and the transducer if a modulated signal from a conductive coil is used.

  The advantages of these implementations is that surgery in the middle ear is not necessary to implant the transducer. In addition, these implementations provide a way for a patient to test a floating mass transducer without undergoing surgery. 40

C. Shell Peg

 The present invention provides an external sound transducer that is connected to the shell as a shell plug. Figure 22 illustrates the placement of the shell plug of the external sound transducer. A small hole or incision is made in the shell and an external sound transducer 800 is inserted into the hole in the shell. The external sound transducer comprises a microphone 802, a sound processor 804, an amplifier 45 806, and a battery inside the battery cover 808. The microphone can also include a microphone tube as shown in Figure 19a. , for a better reception.

  In operation, the external sound transducer is substantially identical in design to a conventional hearing aid transducer. The sound waves are converted into an electrical signal using the microphone and the sound processor of the external sound transducer. The amplifier increases the signal and sends it through 50 810 cables to the front of the QQ shell. At the front of the shell, the cables 810 are electrically connected with the cables 24, which transmit the alternating current signal to a floating mass transducer 100. The transducer 100 can be connected to the tympanic membrane in any of the ways describe and shown with a flexible membrane 502.

  As it may be desirable to have the cables of the external sound transducer and the floating mass transducer 55 detachable, the cables 24 may terminate in a cover 812. The cover is designed with cable connections and can be removed from the external sound transducer. The cover shown is held in position by magnets 814.

V. CONFIGURATION OF THE INTERNAL FLOATING MASS TRANSDUCER

A. Middle ear fixation without disarticulation

 A floating mass transducer according to the present invention can be implanted in the middle ear without disarticulating the ossicles. Figure 5a shows how a floating mass transducer can be held on the anvil. However, a floating mass transducer can also be attached, or otherwise secured (for example, with 5 surgical screws) to any of the ossicles.

  The figure. 23 illustrates how a floating mass transducer can be attached to the oval window in the middle ear. A floating mass transducer 100 can be attached to the oval window with an adhesive, glue, suture thread, and the like. Alternatively, the transducer can be held in position by connecting with the stirrup HH. Fixing the transducer to the oval window provides a direct vibration of the cochlear fluid in the inner ear. In addition, a floating mass transducer can be attached to the middle ear side of the tympanic membrane.

  The fixation of a floating mass transducer in the middle ear without disarticulation provides the advantage that the patient's natural hearing is maintained.

B. Total and partial ossicular replacement prosthesis

 A floating mass transducer can be used in a total or partial ossicular replacement prosthesis, as shown in Figures 8 and 9. The ossicular replacement prosthesis can incorporate any of the floating mass transducers described herein. Therefore, the description of ossicular replacement prostheses in reference to an embodiment of a floating mass transducer does not imply that only that embodiment can be used. One skilled in the art could easily design ossicular replacement prostheses using any of the embodiments of the floating mass transducer of the present invention. twenty

C. Completely internal

 A hearing aid that has a floating mass transducer can also be implanted to be totally internal. In this implementation, a floating mass transducer is fixed in the middle ear in any of the ways described above. One of the difficulties encountered in trying to produce a fully implantable hearing aid is the microphone. However, a floating mass transducer can also function as an internal microphone. 25

 Figure 24 illustrates a fully internal hearing aid that uses a floating mass transducer. A floating mass transducer 950 is fixed by a clip to the hammer LL. The transducer 950 captures the vibration of the hammer and produces an alternating current signal on the cables 952. Therefore, the transducer 950 is the equivalent of an internal microphone.

  A sound processor 960 comprises a battery, an amplifier and a signal processor, which are not shown in detail. The sound processor receives the signal and sends an amplified signal to a floating mass transducer 980 through cables 24. The transducer 980 is fixed to the middle ear (for example, the anvil) to produce vibrations in the oval window that the patient can detect.

  In a preferred embodiment, the sound processor includes a rechargeable battery that is recharged with a pickup coil. The battery is recharged when a recharge coil that has a current flowing through it is placed very close to the pickup coil. Preferably, the volume of the sound processor can be programmed remotely so that it is adjustable by magnetic switches that are adjusted by placing a magnet in the vicinity of the switches.

D. Surgery

 Currently, patients with hearing losses above 50 dB are believed to be the best 40 candidates for an implanted hearing device in accordance with the present invention. Patients suffering from mild to mild-moderate hearing loss may, in the future, be among the potential candidates. Numerous preoperative audiological tests are essential both to identify patients who could benefit from the device and to provide baseline data to compare with post-operative results. In addition, these tests could allow the identification of patients who could benefit from an additional procedure at the time the device is surgically implanted.

  Upon identification of a potential receiver of the device, appropriate guidance should be provided to the patient. The goal of the orientation is, for the surgeon and the audiologist, to provide the patient with all the information necessary to make an informed decision about whether to opt for the device instead of the conventional treatment. The final decision on whether a patient could benefit substantially from the invention should take into account the audiometric data of the patient and his medical history and the patient's feelings regarding the implantation of this device. To help with the decision, the patient should be informed of possible adverse effects, the most common being a slight change in residual hearing. The most serious adverse effects is the possibility of total or partial facial paralysis, resulting from damage to the facial nerve during surgery. In addition, the

Inner ear can also be damaged during device placement. Although it is uncommon due to the use of biocompatible materials, immunological rejection of the device could occur.

  Before surgery, the surgeon must make several patient management decisions. First, the type of anesthesia must be chosen, either general or local; A local anesthetic improves the chance of an intraoperative device test. Secondly, it is necessary to verify the performance of the particular transducer (for example, fixation by means of a clip to the anvil or a partial ossicular replacement prosthesis) that is most suitable for the patient. However, other embodiments should be available during surgery in case an alternative embodiment is necessary.

  A surgical procedure for implanting the implant portion of the device can be reduced to a seven stage process. First, a modified radical mastoidectomy is performed, through which a canal is made through the temporal bone to allow adequate visualization of the ossicles, without interrupting the ossicles chain. Second, a concave part of the mastoid is formed for placement of the receiving coil. The middle ear is also prepared for the installation of the implant, if necessary; that is, other necessary surgical procedures can also be performed at this time. Thirdly, the device (which comprises, as a unit, the transducer connected by means of wires to the receiving laboratory) is inserted through the surgically created channel in the middle ear. Fourth, the transducer is installed in the middle ear and the device is placed or adjusted in position, depending on the performance of the transducer used. As part of this stage, the cables are placed in the channel. Fifthly, the recipient lab is placed inside the concave portion created in the mastoid. (See stage two above). Sixth, after resuscitating the patient sufficiently to respond to the audiological stimuli, the patient is tested intra-operatively 20 after the placement of the external amplification system on the implanted recipient laboratory. In the event that the patient does not pass the intra-operative tests or complains of poor sound quality, the surgeon must determine if the device is correctly attached and place it correctly. In general, the unfavorable test results are due to a bad installation, since the device requires a perfect fit for optimal performance. If it is determined that the device is not operational, a new implant must be installed. Finally, 25 antibiotics are administered to reduce the likelihood of infection, and the patient closes.

  Another surgical procedure for implantation of the implantable portion of the device is performed by simple surgical procedures. The person who wants the internal floating mass transducer prepares for surgery with local anesthesia, as is common in most ear operations. The surgeon makes a post-auricular incision 3-4 cm in length. Then, the surgeon stretches the ear (atrial pavilion) forward with a scalpel, creating a canal along the posterior auditory canal (EAC) between the surface of the bone and the upper skin and fascia. The surgeon cautiously creates the canal (through which the cables will be placed) down the EAC until the annular ring of the tympanic membrane is reached. The annular ring is dissected and folded back to expose the middle ear space. The floating mass transducer is directed through the surgically created channel in the middle ear space and is fixed to the appropriate middle ear structure. A speculum is advantageously used to facilitate this process. A concave basin is formed in the temporal bone posterior to the atrium to hold the receiving coil in position, or a small screw is fixed in the skull to hold the receiving coil over time. The transducer is then checked to see if it is working with a test, in which the subject is asked to simply judge the sound quality of music and speech. If the results are satisfactory, the patient closes. 40

  Post-operative treatment involves procedures usually used after similar types of surgery. Antibiotics and pain medications are prescribed in the same way as after any mastoid surgery, and normal activities that do not prevent proper healing can be resumed within 24-48 hours after the operation. The patient should be seen 7-10 days after the operation to assess wound healing and remove stitches. Four. Five

  After proper healing, the installation of the external amplification system and the tests of the device are performed by an audiologist. The audiologist adjusts the device based on the subjective evaluation of the patient of the position that results in the perception of an optimal sound. In addition, audiological tests should be performed without the external amplification system in place to determine if surgical implantation affects the patient's residual hearing. A final test is performed after all adjustments in order to compare the postoperative audiological data 50 with the basic data before the operation.

  The patient should be seen about thirty days later to measure the device's performance and make the necessary adjustments. If the device works clearly worse than during the test session at the beginning of the post-operative period, the patient's evolution should be followed closely, and surgical adjustment or replacement may be necessary if the audiological results do not improve. In those patients in whom the device operates satisfactorily, semi-annual tests should be performed, which may eventually be annual.

SAW. BONE DRIVING FLOATING MASS TRANSDUCER CONFIGURATION

 Bone conduction is a natural form of hearing. When listening to his own voice, one hears the voice transmitted through the air and transmitted through the bones of the skull (that is, not ossicles). It has been estimated that the fraction of your

own voice that is transmitted by bone conduction is approximately equal to the fraction that is transmitted by air. It is for this reason that most people believe that their recorded voice sounds "funny" because the recorders only record the airborne sounds.

  Bone-driven sound is transmitted to the inner ear through three modes of excitation. First, the sounds are most often emitted to the external ear canal and the middle ear cavity, 5 resulting in the vibration of the ossicles. Second, low frequency sounds accelerate the temporal bone, which causes the vibration of the ossicles and the fluids of the inner ear. Third, medium and high frequency sounds produce dimensional changes in the cochlear deposit, resulting in the excitation of fluids in the inner ear. Although some sounds use the outer and middle ear, bone conduction transmits the sounds in a range of frequencies that the inner ear without relying on the outer and middle ear. The floating mass transducers 10 of the present invention can assist hearing by utilizing bone conduction as follows.

A. Middle ear fixation

 The figure. 25a illustrates a floating mass transducer attached to the bone in the middle ear. An audio processor 1000 receives ambient sounds and transmits the sounds in the form of signals to an implanted receiver 1002. The audio processor typically includes a microphone, circuits that perform both signal processing and signal modulation, a battery and a coil to transmit the signals through different magnetic fields to the receiver. An audio processor that can be used with the present invention is described in US application No. 08 / 526,129, filed on September 7, 1995.

  Receiver 1002 typically includes a coil to receive signals transcutaneously from the audio processor in the form of various magnetic fields. As shown, the receiver is placed under the skin and converts the variable magnetic fields into electrical signals. A demodulator 1004 demodulates the electrical signals that are transmitted to the floating mass transducer 1000 through the cables 24. The cables reach the middle ear through a channel 1006 that has been cut in the temporal bone, as previously discussed.

  The floating mass transducer 100 is fixed to the temporal bone on a promontory below the oval window 25 by a surgical screw 1008. Other fixation mechanisms include bone cement, a plug coated with hydroxy apatite or sutures.

 During operation, the floating mass transducer vibrates in response to the electrical signals produced by the ambient sound. Since the floating mass transducer is securely attached to the skull bone, the vibrations are transmitted to the fluid in the inner ear by bone conduction. It is believed that it will be more efficient to connect the floating mass transducer near the cochlea.

  Figure 25b illustrates another embodiment of the floating mass transducer attached to the bone in the middle ear. As before, an audio processor 1000 receives the ambient sound and transmits the sound in the form of signals to an implanted receiver 1002. The receiver 1002 receives the signals transcutaneously from the audio processor. A demodulator 1004 demodulates the electrical signals that are transmitted to the floating mass transducer 100 through the wires 24. The wires reach the middle ear through the cartilage and the tissue adjacent to the temporal bone and then travel through the external ear canal below the skin. In this way, the cables can pass into the middle ear without piercing the tympanic membrane.

  The floating mass transducer 100 is fixed to the temporal bone above the oval window with a surgical screw 1008. Other fixation mechanisms include bone cement, a plug coated with hydroxy apatite or 40 sutures.

  During operation, the floating mass transducer vibrates in response to the electrical signals produced by the ambient sound. Since the floating mass transducer is securely attached to the skull bone, the vibrations are transmitted to the fluid in the inner ear by bone conduction.

B. Nozzle piece 45

 Figure 26 shows a piece of diving nozzle incorporating floating mass transducers of the present invention. A purge valve 1100 includes a high pressure air line 1102 through which air is forced into an inlet 1104. The purge valve reduces the air pressure through the inlet, so that the diver can breathe . Air is expelled through air exhaust lines 1106. The description of the purge valve is illustrative of a purge valve, but the present invention can easily be used in purge valves 50 of other configurations.

  The purge valve includes a nozzle piece 1108 that is placed in the mouth of the diver. The nozzle includes multiple floating mass transducers. The floating mass transducers are molded into the nozzle piece so that the floating mass transducers contact the diver's teeth. Floating mass transducers can have an acrylic coating to increase durability and improve signal transmission. On a 55

embodiment, the floating mass transducers are molded into the nozzle piece, so that there is a thin layer of the nozzle piece between the floating mass transducer and the teeth. The vibrations of the floating mass transducer are transmitted to the teeth and through the skull to the inner ear.

  Floating mass transducers receive electrical signals through the wires 24 of a receiver that can be placed on the diver's back. Water is really an excellent conductor of sounds, so that the receiver can receive sounds from a transmitter located at a great distance. Typically, the diver will receive the sounds of a ship located on the surface with the ship having a transmitter in the water.

  Although the floating mass transducer has been described in relation to a piece of diving nozzle, floating mass transducers can also be easily used in other nozzle parts. For example, floating mass transducers can be incorporated into a piece of nozzle used by soccer players, so that 10 can listen to instructions and signals, even in full stadiums. The receiver is usually in the player's helmet. Any number of floating mass transducers can be used in a nozzle piece including a single floating mass transducer.

VII. FLOATING MASK TRANSDUCER OF ZUMBID MASK

 Tinnitus is a medical condition when a person hears a constant ringing or ringing in the ears. 15 The effect can at least be described as irritating, and some even describe it as maddening. Although the exact cause of tinnitus cannot be known, a floating mass transducer can be used to mask the sounds of the hum.

  The buzzing sound is often a pure tone that can be masked by a signal that it is 180 ° out of phase with the buzzing sound. In this way, the buzzing sound is effectively neutralized 20 by the floating mass transducer that generates a signal that is 180 ° out of phase with the buzzing sound. The floating mass transducer can be implanted or mounted in any of the ways described herein. It is believed that since the floating mass transducer is based on vibration conduction, it can mask the hum better than conventional acoustic headphones.

  An audio processor can activate the floating mass transducer to produce a signal that masks the hum. In addition, some suffering from tinnitus may find relief in a floating mass transducer that generates a background signal such as "white noise" or sounds of waves on the beach. The humming of the floating mass transducer can be combined with other types of hearing aid.

VIII. EXPERIMENTAL

 The following examples serve to illustrate certain preferred embodiments and aspects of the present invention, and should not be construed as limitations on the scope thereof. The experimental description that follows is divided into: I) Examples of In Vivo corpses, and II) Subjective evaluation of In Vivo voice and music. These two sections summarize the two methods used to obtain in vivo data for the device.

A. Examples of In Vivo corpses

 When the sound waves hit the tympanic membrane, the middle ear structures vibrate in response to the intensity and frequency of the sound. In these examples, a Doppler laser speedometer (LDV) was used to obtain the device's performance curves against sounds of pure tones in the ears of human corpses. The LDV tool that was used for these examples is found at Veterans Administration Hospital in Palo Alto, CA. The tool, which is illustrated by a block diagram in Figure 27, has been widely used to measure the vibratory movement of the middle ear and has been described in Goode et al. Goode et al. He used a similar system 40 to measure the vibratory movement of the living human eardrum in response to sound, the results of which are shown in Figure 28, to demonstrate the validity of the method and to validate the temporal bone model of corpses.

  In each of the three examples that follow, the dissection of the human temporal bone includes a facial recess approach to access the middle ear. After removal of the facial nerve, a small objective of 0.5 mm by 0.5 mm on the side was placed in the stirrup stage; The objective is required to facilitate the return of light to head 45 of the LDV sensor.

  The sound was presented at a sound pressure level (SPL) of 80 dB in the eardrum in each example and measured with an ER-7 probe microphone 3 mm away from the eardrum. An ER-2 headset delivers pure SPL 80 dB tones in the audio range. The sound level remained constant for all frequencies. The movement of the stirrup in response to the sound is measured by the LDV and is recorded digitally by a computer using the 50 FFT ("Fast Fourier Transform"); The process has been automated through a commercially available software program (Tymptest), written for the applicant's laboratory, exclusively for tests on human temporal bones.

  In each example, the first curve of the stirrup vibration in response to the sound served as the basis for comparison with the results obtained with the device. 55

Example 1

4b transducer

Transducer construction: A 4.5 mm diameter by 2.5 mm length transducer, illustrated in Figure 29, uses a 2.5 mm diameter NdFeB magnet. A mylar membrane was attached to a plastic drinking straw 2 mm long by 3 mm in diameter, so that the magnet was inside the straw. The tension of the membrane 5 was tested for what is expected to be the necessary tension in the system by palpating the structure with a stick. A 5 mm biopsy punch is used to make holes in an adhesive piece of paper. One of the resulting paper adhesive discs was placed, with the adhesive side down, at each end of the assembly to ensure that the assembly was centered on the structure of the adhesive paper. A camel hair brush was used to carefully apply the white acrylic paint to the entire outer surface of the coil-shaped structure. The painted coil is allowed to dry between multiple layers. This process reinforced the structure. Once the structure was completely dry, the coil was carefully wrapped with a 44 gauge wire. After an adequate amount of wire was wrapped around the coil, the resulting coil was also painted with acrylic paint to prevent the cable Be separated from the structure. Once dry, a five-minute thin layer of epoxy was applied to the entire outer surface of the structure and allowed to dry. The resulting cables were then stripped and coated with solder (plating).

  Methodology: The transducer was placed between the anvil and the hammer and moved to a "perfect fit" position. The transducer was connected to the output of the Crown amplifier, which was activated by the pure tone computer output. The current was recorded through a 10 ohm resistor in series with transducer 4b. With the transducer in position, the current in the transducer was set at 10 milliamps (mA) and the voltage measured at the transducer was 90 millivolts (mV); the values were constant throughout the entire audio frequency range, although there was a slight variation in the high frequencies above 10 kHz. The pure tones were supplied to the transducer by the computer and the LDV measured the stirrup speed as a result of the excitation of the transducer. The resulting figure later became the offset for the purposes of graphic illustration.

  Results: As Figure 30 shows, the transducer resulted in a gain in frequencies above 25 kHz, but little improvement was observed in frequencies below 2 kHz. The data marked a successful first attempt at manufacturing a transducer small enough to fit inside the middle ear and demonstrated the potential of the device for high-fidelity performance. In addition, the transducer is designed to be fixed to an ossicle only, not to be held in position by the tension between the anvil and the hammer, as was required for the crude prototype used in this example. More advanced prototypes set in a single 30 ossicle are expected to result in improved performance.

Example 2

Transducer 5

Transducer construction: A 3 mm long transducer (similar to transducer 4b, Fig. 31) uses an NdFeB magnet 2 mm in diameter and 1 mm in length. A mylar membrane was attached to a plastic drinking straw 35 mm long by 2.5 mm in diameter so that the magnet was inside the straw. The description of the rest of the construction of the transducer 5 is analogous to that of the transducer 4b in example 1, supra, except that: i) a 3 mm biopsy punch is used instead of a 5 mm biopsy punch, and ii) a 48.3 liter wire is used to wrap the coil structure instead of a 44 gauge wire.

  Methodology: The transducer stuck to the long anvil process with cyanoacrylate glue. The transducer was connected to the Crown amplifier which was activated by the pure tone computer output. The current was recorded through a 10 ohm resistor in series with transducer 5. The current to the transducer was set at 3.3 mA, 4 mA, 11 mA and 20 mA and the voltage measured through the transducer was 1 , 2 V, 1.3 V, 2.2 V and 2.5 V, respectively; the values remained constant throughout the entire audio frequency range, although there was a slight variation in the high frequencies above 10 kHz. The pure tones were supplied to the transducer by the computer, 45 while the LDV measures the stirrup speed, which was subsequently converted to the umbo offset for graphic illustration.

  Results: As shown in Figure 31, transducer 5, a transducer much smaller than transducer 4b, showed a marked improvement in frequencies between 1 and 3.5 kHz, with a maximum power greater than SPL equivalent to 120 dB when compared with stirrup vibrations when activated with sound. fifty

Example 3

Transducer 6

Transducer construction: A 4 mm diameter and 1.6 mm long transducer used an NdFeB magnet 2 mm in diameter by 1 mm in length. A soft silicone gel material (instead of the mylar membrane used in examples 1 and 2) held the magnet in position. The magnet was placed inside a plastic drinking straw of length 55

1.4 mm by 2.5 mm in diameter so that the magnet was inside the straw and the silicone gel material was applied with caution to hold the magnet. The tension of the silicone gel was tested for what was expected to be the necessary tension in the system by palpating the structure with a stick. The description of the rest of the construction of transducer 6 is analogous to that of transducer 4b in example 1, supra, except that: 1) a 4 mm biopsy punch was used instead of a 5 mm biopsy punch, and ii) a 48, 3 litz 5 gauge wire was used to wrap the coil structure instead of a 44 gauge wire.

  Methodology: The transducer was placed between the anvil and the hammer and moved to a "perfect fit" position. The transducer cables were connected to the output of the Crown amplifier that was activated by the pure tone computer output. The current was recorded through a 10 ohm precision resistor in series with transducer 6. In this example, the current to the transducer was set at 0.033 mA, 0.2 mA, 1 mA, 5 mA and the measured voltage in the transducer it was 0.83 mV, 5 mV, 25 mV, 125 mV, respectively, these values were constant throughout the audio frequency range, although there was a slight variation in frequencies above 10 kHz. The pure tones were supplied to the transducer by the computer, while the LDV measures the speed of the stirrup, which was subsequently converted to the umbo offset for graphic illustration.

  Results: As Figure 32 shows, the transducer resulted in a notable improvement in frequencies by 15 above 1.5 kHz, with a maximum power exceeding SPL 120 dB equivalents when compared to the baseline driven vibrations of the stirrup with the sound. The crude prototype has demonstrated the potential of the device for a significant improvement in sound, in terms of gain, which could be expected in those who suffer from severe hearing impairment. As indicated in example 1, the transducer is designed to be connected to an ossicle only, not to be held in position by the tension between the anvil and the hammer, 20 as required by the prototype used in this example. The most advanced prototypes placed in an ossicle are only expected to result in improved performance.

B. Subjective evaluation of voice and music In Vivo

 This example, performed on living human subjects, resulted in a subjective measure of the transducer results in the areas of sound quality for music and speech. Transducer 5, used in example 2, 25 above, was used in this example.

Example 4

 Methodology: A soft silicone gel impression of a tympanic membrane was produced resembling a soft contact lens for the eyes, and the transducer stuck to the concave surface of this impression. The connected silicon transducer and impression were then placed on the tympanic membrane of the subject by an otological surgeon while looking through the external ear canal of the subject with a surgical stereo Zeiss OPMI-1 microscope. The device was centered on the tympanic membrane with a non-magnetic suction tip and held in position with mineral oil through the surface tension between the silicon gel membrane and the tympanic membrane. After installation, the transducer cables were placed against the skin behind the atrium in order to prevent dislocation of the device during the test. The transducer cables were then connected to the output of the Crown D-75 amplifier. The input to the Crown amplifier was a common portable compact disc player (CD). Two CDs were used, one with voice and the other with music. The CD was played and the transducer output level was controlled with the Crown amplifier by the subject. The subject was asked to rate the sound quality of the device.

  Results: The example was performed in two subjects, one with normal hearing and one with a 40 dB sensorineural "biscuit bite" hearing loss. Both subjects reported excellent sound quality for both speech and music, without noticing distortion in either subject. In addition, the subject with hearing impairment indicated that the sound was better than the best high fidelity equipment he had ever heard. It should be remembered that the transducer is not designed to be implanted in a silicone gel membrane attached to the tympanic membrane of the subject. The method described was used because the prototypes of the crude transducer that were tested could never be used in a living human being in the form of an implant, the method was the closest approximation to the actual implantation of a transducer, and the applicant needed to validate the results observed in examples of corpses in vivo with a subjective evaluation of sound quality.

REFERENCES CITED IN THE DESCRIPTION

  This list of references cited by the applicant is intended solely to assist the reader and is not part of the European patent document. Although the utmost care has been taken in its realization, errors or omissions cannot be excluded and the EPO declines any responsibility in this regard.

Patent documents cited in the description

  • US 3870832 A [0019]

  • WO 9501710 A [0020]

 • US 52612995 A [0144]

Claims (13)

 1. Apparatus for improving hearing, comprising:

 an accommodation;

 at least one coil fixed to an external surface of the housing, and 5

 a mass placed inside the housing, where the mass includes a magnet and where the mass is supported by a pressure mechanism so that it is suspended inside the housing, and where the mass vibrates in direct response to a signal externally generated electrical;

 whereby the vibration of the mass causes the inertial vibration of the housing, producing vibrations in the vibratory structure of the ear, where the at least one coil comprises two coils, and wherein said two coils are wound in opposite directions on said accommodation.



2. Apparatus according to claim 1, wherein the dough is coupled to the housing by means of a rotating or cantilever support (242, 310).

 15

 3. Apparatus according to claim 1 or 2, wherein the housing is cylindrical.  4. Apparatus according to the preceding claim, which also comprises: cables (24) connected to the at least one coil to supply the signal to the at least one coil, whereby the interaction of the magnetic fields of the magnet and at least one coil causes the mass to vibrate in response to the signal. twenty 5. Apparatus of any of the preceding claims, wherein the housing is a sealed housing 6. Apparatus according to any of the preceding claims, which also comprises a support mechanism, wherein the support mechanism is a clip, glue, adhesive, Velcro, suture, screw or spring. 7. Apparatus according to claim 1, wherein the housing comprises a notch on the external surface configured to fix the at least one coil. 25 8. Apparatus according to claim 1, wherein the pressure mechanism is restricted by indentations to restrict the linear movement of the magnet within the housing. 9. Procedure for the manufacture of a hearing aid, comprising the steps of:

 provide a housing; place a magnet inside the housing;

 press the magnet inside the housing so that the magnet is suspended inside the housing, so that the magnet can vibrate inside the housing;

 seal the housing; Y

 providing at least one coil fixed to an external surface of the housing, wherein the at least one coil comprises two coils, and in which said two coils are wound in opposite directions on said housing. 35



 10. Method according to claim 9, which also comprises connecting the at least one battery coil to a cable configured to deliver an externally generated signal, thereby generating an auditory device. 11. A method according to claim 9 or 10, wherein the resulting hearing device is configured such that

I. The interaction of the magnetic fields of the magnet and of the at least one coil causes the magnet to vibrate inside the housing in response to the externally generated signal; Y

II. The vibration of the magnet causes the inertial vibration of the housing to produce vibrations in a vibrating structure of the ear.

12. Method according to any of claims 9 to 11, wherein said housing comprises a notch on the external surface configured to fix the at least one coil.