U.S. patent application number 10/872737 was filed with the patent office on 2004-11-18 for hybrid implantable cochlear stimulator hearing aid system.
Invention is credited to Balkany, Thomas J., Harrison, William Vanbrooks, Kuzma, Janusz A., Mann, Alfred E..
Application Number | 20040230254 10/872737 |
Document ID | / |
Family ID | 32473978 |
Filed Date | 2004-11-18 |
United States Patent
Application |
20040230254 |
Kind Code |
A1 |
Harrison, William Vanbrooks ;
et al. |
November 18, 2004 |
Hybrid implantable cochlear stimulator hearing aid system
Abstract
A hybrid cochlear implant hearing aid system provides low
frequency acoustic energy boost, if needed, and high frequency
direct neural stimulation. Tinnitus suppression may also be
provided. The neurons responsible for sensing high frequency sounds
are located at the basal end of the cochlea. A short basal
electrode that extends into the cochlea only at the basal region
allows direct stimulation of these neurons by an
appropriately-controlled cochlear stimulator. The basal electrode
array typically has from four to eight electrode contacts. The
hybrid implantable cochlear stimulator and hearing aid system
relies primarily on the cochlear stimulator portion of the system
for being able to sense high frequency sounds, and relies primarily
on normal hearing processes, or other acoustic boosting devices and
systems, for being able to sense lower frequency sounds.
Inventors: |
Harrison, William Vanbrooks;
(Valencia, CA) ; Kuzma, Janusz A.; (Parker,
CO) ; Mann, Alfred E.; (Beverly Hills, CA) ;
Balkany, Thomas J.; (Coral Gables, FL) |
Correspondence
Address: |
ADVANCED BIONICS CORPORATION
25129 RYE CANYON ROAD
VALENCIA
CA
91355
US
|
Family ID: |
32473978 |
Appl. No.: |
10/872737 |
Filed: |
June 21, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10872737 |
Jun 21, 2004 |
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09979804 |
Nov 13, 2001 |
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6754537 |
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09979804 |
Nov 13, 2001 |
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PCT/US00/13122 |
May 12, 2000 |
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60134289 |
May 14, 1999 |
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Current U.S.
Class: |
607/57 |
Current CPC
Class: |
A61N 1/36038 20170801;
A61N 1/0541 20130101; A61N 1/36036 20170801 |
Class at
Publication: |
607/057 |
International
Class: |
A61N 001/18 |
Claims
What is claimed is:
1. A hybrid cochlear stimulator and hearing aid system comprising:
a cochlear electrode array, having a plurality of spaced apart
electrodes thereon, adapted for insertion into the basal region of
the scala tympani duct of a human cochlea; an implantable
stimulator electrically connected to the electrodes on the cochlear
electrode array; a microphone for sensing acoustic sounds and
converting the sensed acoustic sounds to electrical signals; and a
signal processor for processing the electrical signals and
generating high-frequency control signals therefrom representative
of the higher frequency content of the sensed acoustic sounds; the
implantable stimulator having means responsive to the
high-frequency control signals generated by the signal processor
for selectively generating electrical stimuli and applying the
electrical stimuli to the electrodes of the electrode array,
whereby the basal region of the scala tympani duct is stimulated
with electrical stimuli representative of the higher-frequency
content of the sensed acoustic sounds.
2. The hybrid system of claim 1 further including an acoustic boost
device for amplifying the lower frequency content of the sensed
acoustic sounds.
3. The hybrid system of claim 2 further including compensation and
balancing means for providing a smooth transition from lower
frequencies sensed with the aid of the acoustic boost device to the
higher frequencies stimulated through the cochlear electrode array
and implantable stimulator.
4. The hybrid system of claim 2 wherein the acoustic boost device
comprises a hearing aid adapted to be placed in the ear canal of a
user.
5. The hybrid system of claim 2 wherein the acoustic boost device
comprises a middle ear hearing aid system.
6. The hybrid system of claim 5 wherein the middle ear includes a
malleus and a stapes, and wherein the middle ear hearing aid system
includes an implantable acoustic microphone adapted to be coupled
to the malleus, and an implanted acoustic amplifier and driver
adapted to be coupled to the stapes.
7. The hybrid system of claim 6 wherein the middle ear hearing aid
system and the signal processor share common front-end processing
circuitry.
8. The hybrid system of claim 1 further including means coupled
with the signal processor for generating specific sequences of
electrical stimulation pulses applied through the electrodes on the
cochlear electrode array that suppress tinnitus.
Description
[0001] The present application is a Continuation of U.S.
application Ser. No. 09/979,804, filed Nov. 13, 2001 (to be issued
as U.S. Pat. No. 6,754,537 on Jun. 22, 2004), which application
claims the benefit of International Application Number
PCT/US00/13122, filed May 12, 2000, which claims the benefit of
U.S. Provisional Patent Application No. 60/134,289, filed May 14,
1999, all of which applications are incorporated herein by
reference in their entireties.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to hearing aid systems, and
more particularly to a hybrid hearing aid system that combines a
cochlear stimulator and a hearing aid to provide a hearing aid
system that relies primarily on the cochlear stimulator portion of
the system for being able to sense high frequency sounds, and that
relies primarily on normal hearing processes, or a hearing aid, for
being able to sense lower frequency sounds. Such hybrid hearing aid
system is best suited for use with a short cochlear electrode array
of the type described in applicant's copending patent application,
filed concurrently herewith, entitled "Electrode Array for Hybrid
Cochlear Stimulator" (Attorney Docket Number AB-084-PC), which
application is incorporated herein by reference.
[0003] A hybrid cochlear stimulation system provides electrical
stimulation only to the basal end of the cochlea to stimulate
ganglion cells responsible for sensing higher-frequency sounds, and
relies on normal hearing (activation of hair cells through fluid
motion within the cochlea), which may occur with or without the
assistance of a conventional or a custom hearing aid, to sense
middle-to-lower frequency sounds.
[0004] Hearing loss is generally of two types: conductive and
sensorineural. Of these, conductive hearing loss occurs where the
normal mechanical pathways for sound to reach the hair cells in the
cochlea are impeded, for example, by damage to the ossicles.
Conductive hearing loss may often be helped by use of conventional
hearing aids, which amplify sound so that acoustic information does
reach the cochlea and the hair cells. Some types of conductive
hearing loss are also amenable to alleviation by surgical
procedures.
[0005] Sensorineural hearing loss, on the other hand, results due
to the absence or the destruction of the hair cells in the cochlea
which are needed to transduce acoustic signals into auditory nerve
impulses. Persons who suffer from sensorineural hearing loss are
unable to derive any benefit from conventional hearing aid systems,
no matter how loud the acoustic stimulus is made, because their
mechanisms for transducing sound energy into auditory nerve
impulses have been damaged. Thus, in the absence of properly
functioning hair cells, there is no way auditory nerve impulses can
be generated directly from sounds.
[0006] To overcome sensorineural deafness, there have been
developed numerous cochlear implant systems--or cochlear
prosthesis--which seek to bypass the hair cells in the cochlea by
presenting electrical stimuli directly to the ganglia of the
auditory nerve located adjacent the modiolar wall of the cochlea.
When triggered, the ganglia, also referred to as ganglion cells
send nerve impulses to the brain via the auditory nerve, leading to
the perception of sound in the brain, and an at least partial
restoration of hearing function. The common denominator in these
cochlear prosthesis systems has been the implantation into the
cochlea of electrodes which are responsive to a suitable external
source of electrical stimuli and which are intended to transmit
those stimuli to the ganglion cells, and thereby to the auditory
nerve fibers.
[0007] As people age, they frequently experience progressive
hearing loss. Usually this loss is more prevalent and more sever at
higher frequencies. Thus, it is estimated that a large segment of
the hearing-impaired population exhibit sensorineural hearing loss
relative to high frequency sounds, but maintain the ability to
transduce middle-to-lower frequency sounds through functioning hair
cells.
[0008] The usual method to restore this high frequency hearing loss
is by using a hearing aid that increases the amplitude of the
acoustic energy applied to the tympani membrane. Although
effective, this approach does not provide the same level of
restoration to high frequencies as it does to lower frequencies.
Also, the increase in acoustic amplitudes used in this method can
ofttimes further degrade residual hearing, resulting in a further
decrease in the ability to hear the higher frequencies.
[0009] It is thus evident that there is thus a need for a "hybrid"
cochlear stimulation system that electrically stimulates only the
ganglion cells responsible for sensing higher frequency sounds,
while allowing or permitting the normal hearing process (e.g.,
activation of hair cells through wave motion of the fluid within
the cochlea) to function for the purpose of sensing lower-to-middle
frequency sounds.
[0010] A cochlear prosthesis operates by direct electrical
stimulation of the auditory nerve cells, bypassing the defective
cochlear hair cells that normally transduce acoustic energy into
electrical activity in such nerve cells. Because the ganglion cells
responsible for sensing higher frequency sounds are all generally
located in or near the basal end of the cochlea (the end of the
cochlea nearest the basal membrane), a hybrid cochlear stimulation
system thus requires an electrode array that can be inserted within
the cochlea a sufficient depth to be near such cells, but which
also does not block or significantly interfere with the normal
functioning of the cochlea for hair cells located deeper within the
cochlea. Thus, there is a need for such an electrode array that may
be used with a hybrid implantable cochlear stimulator hearing aid
system.
SUMMARY OF THE INVENTION
[0011] The present invention addresses the above and other needs by
providing a hybrid implantable cochlear stimulator and hearing aid
system that relies primarily on the cochlear stimulator portion of
the system for being able to sense high frequency sounds, and that
relies primarily on normal hearing processes, or other acoustic
boosting devices and systems, for being able to sense lower
frequency sounds. Such hybrid hearing aid system uses a relatively
short and unobtrusive cochlear electrode array, e.g., of 6-8 mm in
length, of the type described in applicant's copending patent
application, previously referenced, entitled "Electrode Array for
Hybrid Cochlear Stimulator" (Attorney Docket Number AB-084-PC), or
something equivalent thereto.
[0012] A hybrid cochlear implant hearing aid system in accordance
with the present invention provides low frequency acoustic energy
boost, if needed, and high frequency direct neural stimulation. The
high frequency neurons are located at the basal end of the cochlea,
providing easy access for the surgical placement of a short
electrode that stimulates only the high frequencies. The electrode
array typically has from four to eight electrode contacts, e.g., 4
or 5 electrode contacts. The design of the electrode array allows
the surgeon to place the array using minimally invasive surgical
techniques and requires no cochleostomy. The electrode array is
thin, and can typically be inserted directly through the round
window membrane to make contact with, or to be positioned in close
proximity to, the modiolus wall in the basal region of the
cochlea.
[0013] The front-end amplifier and processor and spectral
decomposition filters used with the hybrid system of the present
invention may be the same for both acoustic boost and neural
stimulation applications. The frequencies are separated and sent to
circuits that either convert them into mechanical vibrations to
boost low-to-middle frequency acoustic energy, or into high
frequency energy that is further divided and converted to
stimulation pulses that are applied directly to the neurons located
in the basal region of the cochlea through the short electrode. A
smoothing circuit may be provided to allow a smooth, seamless
transition from the acoustic enhancement provided for low-to-middle
frequencies and the neural stimulation provided for the high
frequencies.
[0014] In accordance with one aspect of the invention, tinnitus
(which is a buzzing, or ringing, sound in the ear) is suppressed by
delivering special pulse sequences on some of the electrodes
located in the basal region of the cochlea, while acoustic
enhancement is provided in the low frequency range.
[0015] Advantageously, the hybrid system of the present invention
may be used for several applications. Such applications include,
but are not limited to:
[0016] (a) high frequency neural stimulation combined with residual
low frequency hearing;
[0017] (b) high frequency neural stimulation signal enhancement
combined with low frequency acoustic signal enhancement;
[0018] (c) tinnitus suppression;
[0019] (d) tinnitus suppression combined with acoustic signal
enhancement;
[0020] (e) high frequency neural stimulation signal enhancement,
acoustic signal enhancement, and tinnitus suppression stimulation;
or
[0021] (f) tinnitus suppression combined with cochlear neural
stimulation.
[0022] It is thus a feature of the present invention to provide a
hybrid cochlear stimulation and hearing aid system that restores
hearing function over a wide frequency band, e.g., from low
frequencies to high frequencies.
[0023] It is a further feature of the invention to provide such a
hybrid system wherein minimally invasive surgical techniques are
employed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] The above and other aspects, features and advantages of the
present invention will be more apparent from the following more
particular description thereof, presented in conjunction with the
following drawings wherein:
[0025] FIG. 1 is a functional schematic diagram of the ear, showing
the manner in which an implantable cochlear stimulator and short
cochlear electrode in the basal region of the cochlea may be used
to practice the invention in accordance with one embodiment
thereof;
[0026] FIG. 2 is a functional schematic diagram of the ear as in
FIG. 1, and further shows the manner in which a conventional
in-the-ear hearing aid may be used to supplement the practice of
the invention;
[0027] FIG. 3 is a functional schematic diagram of the ear as in
FIGS. 1 and 2, and further shows how a middle-ear acoustic boosting
system or hearing-aid device may be used as part of the hybrid
system of the invention; and
[0028] FIG. 4 is a block diagram of the signal processing portions
of the invention.
[0029] Corresponding reference characters indicate corresponding
components or elements throughout the several views of the
drawings.
DETAILED DESCRIPTION OF THE INVENTION
[0030] The following description is of the best mode presently
contemplated for carrying out the invention. This description is
not to be taken in a limiting sense, but is made merely for the
purpose of describing the general principles of the invention. The
scope of the invention should be determined with reference to the
claims.
[0031] Turning first to FIG. 1, one embodiment of the hybrid
cochlear stimulation system of the present invention is shown. Such
embodiment relies upon an implantable cochlear stimulator (ICS) 50
to provide direct electrical stimulation of the ganglion cells
located at the basal end of the cochlea, to thereby enhance the
hearing of high frequency sounds; and relies upon the patient's
normal hearing processes, e.g., the patient's residual low and mid
frequency hearing, to sense low-to-mid frequency sounds.
[0032] As seen in FIG. 1, the major relevant components of the
outer, middle and inner ear are illustrated. To better understand
the present invention, It will first be helpful to briefly review
the normal operation of a fully functional ear. Thus, as seen in
FIG. 1, the outer ear includes the auricle 14 and the ear canal 16.
An acoustic pressure wave, or sound wave, represented in FIG. 1 by
the short parallel lines 12, is collected by the auricle 14 and
funneled into the ear canal 16. At the end of the ear cannel 16 is
the "ear drum" 18, or in medical terms, the tympanic membrane 18.
In a person who is not significantly hearing impaired, the received
acoustic wave 12 causes the tympanic membrane 18 to vibrate, which
vibration is coupled through three tiny bones, the malleus
("hammer") 20, the incus ("anvil") 22 and the stapes ("stirrup")
24, to the fenestra 30.
[0033] In anatomical terms, the fenestra comprises an opening
resembling a window. The fenestra ovalis, or oval window, is the
opening between the middle ear and the vestibule of the inner ear.
It is closed by a membrane to which the stapes is attached. The
fenestra rotunda, or round window, is the opening between the scala
tympani of the cochlea and the middle ear. The round window is also
closed by a membrane, which for purposes of the present
application, may be referred to as the round window membrane. For
purposes of the schematic diagram shown in FIG. 1, as well as the
other figures presented herein, the function of both the oval
window and round window is represented by the single membrane
30.
[0034] The bones of the middle ear serve to filter and amplify the
perceived acoustic wave 12, causing the fenestra membrane 30 to
articulate, or vibrate, in response to the acoustic wave 12.
Vibration of the membrane 30 sets up waves of fluid motion within
the fluid contained within the snail-shaped cochlea 36. Such fluid
motion, in turn, activates tiny hair cells (not shown in FIG. 1)
that line the inside of the cochlea 36. Activation of the hair
cells causes appropriate nerve impulses to be transferred through
the spiral ganglion 40 to the brain, where they are perceived as
sound.
[0035] The spiral ganglion cells that are responsible for the
perception of high frequency sounds are generally located at the
basal end of the cochlea 36, i.e., that end of the cochlea closest
to the membrane 30. For those individuals who suffer from high
frequency hearing loss, the hair cells in the basal region of the
cochlea are ineffective or otherwise damaged to the point where it
is not possible to activate them. Hence, in accordance with the
present invention, an implantable cochlear stimulator (ICS) 50 may
be implanted near the ear, and a short cochlear electrode array 52,
having a plurality of spaced apart electrodes 54 thereon, is
inserted into the cochlea 36 through the membrane 30. (In practice,
the electrode array 52 may be inserted directly through a slit made
in the round window.) Such ICS 50 is coupled to a microphone, e.g.,
an external microphone 40 (although an internal, i.e., implanted,
microphone could also be used) that senses sounds. The microphone
signals are amplified and processed by a suitable speech processor
(S.P.) 42, which S.P. may also be external or implanted. The speech
processor generates appropriate control signals that are coupled to
the ICS 50. Such coupling may occur through various means, but is
usually achieved through an inductive coupling link, represented by
the arrow 44, with an external head piece, connected to the speech
processor 42. Such link also provides a way for power to be coupled
into the implanted ICS 50. However, it is also possible for the
processor and power source to be implanted, either as an integral
part of the ICS 50 or in a separate housing coupled to the ICS.
(See, e.g., International Publication No. WO 99/06108, published 11
Feb. 1999, incorporated herein by reference.)
[0036] In operation, the speech processor 42 functions as a signal
processing means for processing the electrical signals received
from the microphone and for generating high-frequency control
signals therefrom representative of the higher frequency content of
the sensed acoustic sounds. These control signals are then coupled
to the ICS 50 through the link 44. The ICS 50 has means responsive
to the high-frequency control signals for selectively generating
electrical stimuli and applying the electrical stimuli to the
electrode (52). In this manner, the basal region of the scala
tympani duct is stimulated with electrical stimuli representative
of the higher-frequency content of the sensed acoustic sounds.
[0037] In accordance with the embodiment of the invention depicted
in FIG. 1, the sounds sensed by the microphone 40 are processed and
filtered to separate out the high frequency sounds. These high
frequency sounds are then converted to appropriate electrical
stimuli that are selectively applied to the electrode contacts 54
of the electrode array 52 positioned in the basal region of the
cochlea. Such electrical stimuli bypass the defective hair cells in
the basal region of the cochlea and directly activate the nerves
within the of the spiral ganglion, causing nerve impulses to be
transferred to the brain, where they may be perceived as high
frequency sounds.
[0038] The other hair cells in the cochlea, i.e., those in the
apical and mid regions of the scala tympani duct, retain their
functionality. That is, these hair cells are able to sense the
fluid waves set up by vibrations of the membrane 30 corresponding
to low-to-mid frequency sounds. Hence, the patient (or user of the
hybrid system shown in FIG. 1) is able to sense high frequency
sounds through the ICS portion of the system, and is able to sense
lower frequency sounds through the normal hearing processes of the
ear.
[0039] In FIG. 2, another embodiment of the invention is depicted.
The embodiment shown in FIG. 2 is the same as the embodiment shown
in FIG. 1 except for the addition of an in-the-canal hearing aid
15. The in-the-canal hearing aid 15, which may be of conventional
design, receives the acoustic waves 12 and amplifies them, thereby
presenting amplified acoustic waves 13 to the tympanic membrane 18.
The amplified acoustic waves 13 are thereby able to increase the
magnitude of the vibrations that pass through the middle ear and
articulate the membrane 30, thereby increasing the magnitude of the
fluid waves within the cochlea, which higher-magnitude fluid waves
may be more effective at activating the hair cells throughout the
cochlea. Typically, however, the high-frequency hair cells at the
basal end of the cochlea remain defective and unresponsive to the
higher-magnitude fluid waves. Thus, the cochlear stimulator portion
(ICS 50 and electrode array 52) of the hybrid system must still be
used if high frequency sounds are to be perceived.
[0040] Turning next to FIG. 3, yet another embodiment of the
invention is shown, comprising a middle ear hearing aid system 60
which is inserted into the middle ear. Such system 60 includes an
implanted acoustic microphone 62 attached to the malleus 20 and an
implanted acoustic amplifier and driver 64 coupled to the stapes
24. Thus, as acoustic signals vibrate the tympanic membrane, such
signals are sensed by the microphone 62 attached to the malleus 20
and transduced to an electrical or other (e.g., optical or
magnetic) signal. This signal is then applied to the acoustic
amplifier and driver device 64, where they are transduced back to
mechanical vibrations that drive the stapes 24, and hence vibrate
the membrane 30 with an amplified or increased intensity. The
vibration of the membrane 30 with an increased intensity or
magnitude, in turn, increases the intensity of the fluid waves that
are set up within the scala tympanic duct of the cochlea, thereby
more effectively activating the non-defective hair cells throughout
the cochlea. For a hearing impaired individual, having defective
high frequency hair cells, such middle ear hearing aid system 60
thus provides an increased ability to sense lower frequency
acoustic signals. To sense high frequency sounds, a stimulator
circuit 50', coupled to the basal electrode array 52, senses the
high frequency sounds and converts them to appropriate electrical
stimuli for application to the respective electrode contacts 54 on
the electrode array 52.
[0041] Turning next to FIG. 4, a block diagram of the signal
processing circuits used by the hybrid system of FIG. 3 is
depicted. As seen in FIG. 4, a front-end amplifier and processor
70, including an analog-to-digital converter (ADC), senses acoustic
signals. The processor further uses appropriate spectral
decomposition filters to separate the high frequency signal
components from the low and middle frequency components. The high
frequency signal components are then sent to a cochlear signal
processor 72, and the low and middle frequency signal components
are sent to an acoustic signal processor 74. Each of these
processors 72 and 74 applies appropriate signal processing
strategies to the signals and then applies them to a signal phase
compensation and balance processor 76. This phase compensator and
balance processor performs, inter alia, a smoothing function that
allows a smooth, seamless transition from the acoustic enhancement
provided for low-to-middle frequencies and the neural stimulation
provided for the higher frequencies. After balancing and phase
compensation, which may be considered as "signal enhancement", the
acoustic signals are sent to the output-to-acoustic amplifier and
driver circuit 64 and the cochlear stimulator signals are sent to
the stimulator circuits 50'. At the output-to-acoustic amplifier
and driver circuit 64, the signals are converted into mechanical
vibrations to boost low-to-middle frequency acoustic energy. At the
cochlear stimulator circuits 50', the signals are converted into
high frequency energy that is further divided and converted into
stimulation pulses that are applied directly to the neurons located
in the basal region of the cochlea through the short basal
electrode 52.
[0042] One important aspect of the invention relates to its ability
to suppress tinnitus. Tinnitus suppression is carried out by
generating appropriate pulse sequences in the stimulator 50 or 50'
and then delivering these pulse sequences to selected electrodes 54
on the electrode array 52. Such suppression may occur at the same
time that acoustic enhancement takes place for the lower
frequencies.
[0043] The various components of the invention, i.e., high
frequency neural stimulation, residual lower frequency hearing,
high frequency neural stimulation with signal enhancement, lower
frequency acoustic signal enhancement, and tinnitus suppression,
may advantageously be combined in various ways to address several
different applications. For example, the invention may be used for
any or all of the following applications:
[0044] (a) high frequency neural stimulation combined with residual
lower frequency hearing;
[0045] (b) high frequency neural stimulation signal enhancement
combined with lower frequency acoustic signal enhancement;
[0046] (c) tinnitus suppression;
[0047] (d) tinnitus suppression combined with acoustic signal
enhancement;
[0048] (e) higher frequency neural stimulation signal enhancement,
acoustic signal enhancement, and tinnitus suppression stimulation;
or
[0049] (f) tinnitus suppression combined with cochlear neural
stimulation.
[0050] As described above, it is thus seen that the present
invention provides a versatile hybrid cochlear stimulation and
hearing aid system that may restore hearing function over a wide
frequency band, e.g., from low frequencies to high frequencies.
[0051] As described above, it is further seen that the invention
provides such a hybrid system wherein minimally invasive surgical
techniques need be employed.
[0052] As described above, it is additionally seen that the
invention provides a versatile hybrid system that can be used for a
wide variety of applications, ranging from higher frequency neural
stimulation, with or without signal enhancement (balancing,
smoothing and phase compensation); tinnitus suppression; residual
lower frequency hearing, or lower frequency acoustic signal
enhancement.
[0053] While the invention herein disclosed has been described by
means of specific embodiments and applications thereof, numerous
modifications and variations could be made thereto by those skilled
in the art without departing from the scope of the invention set
forth in the claims.
* * * * *