Surgery – Surgically implanted vibratory hearing aid
Reexamination Certificate
1999-08-17
2001-02-20
O'Connor, Cary (Department: 3736)
Surgery
Surgically implanted vibratory hearing aid
C607S055000, C607S057000
Reexamination Certificate
active
06190306
ABSTRACT:
THE FIELD OF THE INVENTION
This invention relates generally to at least partially implantable hearing assistance systems, and more particularly to the sensing of sound vibrations in the middle ear.
BACKGROUND
Some types of partial middle ear implantable (P-MEI), total middle ear implantable (T-MEI), cochlear implant, or other hearing assistance systems utilize components disposed within the middle ear or inner ear regions. Such components may include an input transducer for receiving sound vibrations or an output stimulator for providing mechanical or electrical output stimuli corresponding to the received sound vibrations.
An example of such a device is disclosed in U.S. Pat. No. 4,729,366, issued to D. W. Schaefer on Mar. 8, 1988. In the '366 patent, a mechanical-to-electrical piezoelectric input transducer is associated with the malleus bone in the patient's middle ear. The malleus vibrates in response to sounds received at the patient's tympanic membrane (eardrum). The piezoelectric input transducer transduces mechanical energy of malleus vibrations into an electrical signal, which is amplified and further processed by an electronics unit. A resulting electrical signal is provided to an electrical-to-mechanical piezoelectric output transducer that generates a mechanical vibration coupled to an element of the ossicular chain or to the oval window or round window. In the '366 patent, the ossicular chain is interrupted by removal of the incus. Removal of the incus prevents the mechanical vibrations delivered by the piezoelectric output transducer from mechanically feeding back to the piezoelectric input transducer.
Another example of such a device is disclosed in U.S. Pat. No. 5,554,096 issued to G. R. Ball on Sep. 10, 1996. In the '096 patent, an external transducer senses sound. A resulting electrical signal is processed and provided to a subcutaneous electromagnetic transducer. In the '096 patent, the electromagnetic transducer is used for vibrating an ossicle.
Another example of such a device is disclosed in U.S. Pat. No. 5,558,618 issued to A. J. Maniglia on Sep. 24, 1996. In the '618 patent, acoustic signals are transduced into electrical signals by external means. A resulting electrical signal is provided to actuate an electromagnet for assisting hearing.
Hearing assistance systems that use piezoelectric input transducers to sense sounds through corresponding ossicular vibrations face numerous difficulties. For example, the bandwidth of the piezoelectric input transducer may not accommodate the full frequency band between 250 Hertz and 5 kilohertz needed for good speech comprehension. Piezoelectric input transducers also typically suffer from a highly nonlinear frequency response due to a resonance frequency in or near the audio frequency range. Piezoelectric input transducers can be quite fragile. In addition, a piezoelectric input transducer typically requires rigid mechanical contact with the auditory element, which results in a mechanical loading that can diminish the gain and frequency sensitivity of the sensed mechanical sound vibrations.
For the reasons stated above, and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for sensing middle ear sound vibrations through input transducers that do not have the above-described limitations of piezoelectric input transducers.
SUMMARY
The present invention provides a hearing assistance system that includes non-piezoelectric input sensors for transducing vibrations in the middle ear into electrical signals. One embodiment of the invention includes a sensor for transducing mechanical sound vibrations in a middle ear into an electrical input signal. The sensor includes a capacitor having a first portion that is coupled (e.g., mechanically, magnetically, or otherwise) to an auditory element for receiving the vibrations and changing a capacitance value of the capacitor in response thereto.
According to one aspect of the invention, the sensor may be pivotably coupled to at least one of the auditory element and a carrier secured in the middle ear. Another embodiment includes middle-ear implantable hearing assistance system comprising a capacitive sensor, coupled to an auditory element for receiving vibrations and varying a capacitance value in response thereto. An amplifier is electrically coupled to the capacitive sensor for amplifying a signal resulting from the varying capacitance value. An output stimulator receives a signal based on the varying capacitance value, and provides a resulting stimulus to an auditory element.
The invention also provides a method of transducing a mechanical vibration of an auditory element into at least one electrical signal. A capacitive sensor is coupled to the auditory element for receiving the vibrations, thereby resulting in capacitance variations. The capacitance variations are sensed. An electrical signal is provided in response to the sensed capacitance variations. In one embodiment, the hearing assistance system includes an external programmer for adjusting hearing assistance parameters in a hearing assistance device and for data transmission from the hearing assistance device to the programmer, such as for parameter verification or diagnostic purposes.
Thus, the present invention provides an alternative to piezoelectric input transducers, which have limited and nonlinear frequency characteristics, potential reliability problems associated with their durability, and mechanical loading that can diminish the gain and frequency sensitivity of the sensed mechanical sound vibrations.
REFERENCES:
patent: 4840178 (1989-06-01), Heide et al.
patent: 4957478 (1990-09-01), Maniglia
patent: 5015224 (1991-05-01), Maniglia
patent: 5498226 (1996-03-01), Lenkauskas
patent: 5531787 (1996-07-01), Lesinski et al.
patent: 5558618 (1996-09-01), Maniglia
Fredrikson & Byron , P.A.
Marmor II Charles
O'Connor Cary
St. Croix Medical, Inc.
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