U.S. patent number RE43,519 [Application Number 11/099,518] was granted by the patent office on 2012-07-17 for electromagnetically protected hearing aids.
This patent grant is currently assigned to Acacia Patent Acquisition Corporation. Invention is credited to Louis T. Gnecco, Paula S. Gnecco.
United States Patent |
RE43,519 |
Gnecco , et al. |
July 17, 2012 |
**Please see images for:
( Certificate of Correction ) ** |
Electromagnetically protected hearing aids
Abstract
A Behind The Ear, In The Ear, All in The Ear, In The Canal, or
Completely In The Canal hearing aid which is made resistant to
electromagnetic interference produced by cellular telephones in the
800 MHz to 100 GHz frequency range. The resultant hearing aid will
allow hearing impaired people to take advantage of cellular
telephones and other recently-developed personal communication
devices while also using their hearing aids.
Inventors: |
Gnecco; Louis T. (Vienna,
VA), Gnecco; Paula S. (Vienna, VA) |
Assignee: |
Acacia Patent Acquisition
Corporation (Newport Beach, CA)
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Family
ID: |
46465646 |
Appl.
No.: |
11/099,518 |
Filed: |
April 8, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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08835350 |
Apr 7, 1997 |
6031923 |
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08557999 |
Nov 13, 1995 |
5640457 |
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Reissue of: |
09476131 |
Jan 3, 2000 |
6546109 |
Apr 8, 2003 |
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Current U.S.
Class: |
381/322; 381/328;
174/353 |
Current CPC
Class: |
H04R
25/60 (20130101); H04R 2225/025 (20130101); H04R
2225/49 (20130101); H04R 2225/021 (20130101); H04R
2225/023 (20130101); H04R 25/609 (20190501); H04R
2225/57 (20190501); H04R 25/603 (20190501); H04R
25/658 (20130101) |
Current International
Class: |
H04R
25/00 (20060101) |
Field of
Search: |
;381/312,322,324,328,330,189 ;361/816,818,328,306.3 ;174/350,353
;455/100,350,352,575.5,300 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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4011438 |
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Oct 1991 |
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DE |
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43 43 703 |
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Jan 1995 |
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DE |
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4 271398 |
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Sep 1992 |
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JP |
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Other References
"EMC For Product Designers", Butterworth-Heinemann Ltd. 1992, pp.
4-5, 10-11, 122-139, 147-150, 155-158, 166-169, 182-185, 194-195,
199-212. cited by other .
Joyner, et al., "Interference to Hearing Aids by the new Digital
Mobile Telephone System, Global System for Mobile (GSM)
Communications Standard," published by National Acoustic
Laboratories, Mar. 30, 1993; pp. 1-15. cited by other .
LeStrange, R. et al., "Interference to Hearing Aids by the new
Digital Mobile Telephone System, Global System for Mobile (GSM)
Communications Standard", published by National Acoustic
Laboratories, NAL Report No. 131, May 1995, pp. i-x, 1-109. cited
by other .
Oticontact Newsletter, No. 13, Oct. 1993, pp. 1-2. cited by other
.
Office Action dated Apr. 3, 2008 for related co-pending
Reexamination Control. No. 90/008,600. cited by other .
Office Action dated Apr. 3, 2008 in related copending Reexamination
Control No. 90/008,600. cited by other .
Order Granting Ex Parte Reexamination dated Sep. 1, 2007 in related
copending Reexamination Control No. 90/008,600. cited by other
.
Order Granting Ex Parte Reexamination dated Nov. 6, 2007 in related
copending Reexamination Control No. 90/008,607. cited by other
.
Machine translation in English of Mueller et al. (DE 4011438 A1).
cited by other .
Request for Ex Parte Reexamination of U.S. Patent No. 6,031,923;
dated Apr. 19, 2007; pp. 1-28. cited by other .
Reply by Third Party Requester to Patent Owner's Statement Dated
Nov. 1, 2007 from Ex Parte Reexamination Control No. 90/008,600;
Dec. 28, 2007; pp. 1-8. cited by other .
Notice of Intent to Issue Ex Parte Reexamination Certificate from
Ex Parte Reexamination Control No. 90/008,600; mailed Feb. 12,
2009; 9 pages. cited by other .
Request for Ex Parte Reexamination of U.S. Patent No. 5,640,457;
dated Apr. 19, 2007; pp. 1-21. cited by other .
Reply by Third Party Requester to Patent Owner's Statement Dated
Jan. 7, 2007 from Ex Parte Reexamination Control No. 90/008,607;
Mar. 7, 2008; pp. 1-7. cited by other .
Office Action mailed Sep. 19, 2008 from Ex Parte Reexamination
Control No. 90/008,607; 20 pages. cited by other .
Final Office Action mailed Mar. 18, 2009 from Ex Parte
Reexamination Control No. 90/008,607; 22 pages. cited by other
.
Notice of Intent to Issue Ex Parte Reexamination Certificate from
Ex Parte Reexamination Control No. 90/008,607; mailed Jul. 14,
2009; 8 pages. cited by other .
Ex Parte Reexamination Certificate No. US 6,031,923 C1; issued Apr.
21, 2009; 2 pages. cited by other .
Ex Parte Reexamination Certificate No. US 5,640,457 C2; Issued Nov.
3, 2009; 2 pages. cited by other.
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Primary Examiner: Le; Huyen D
Attorney, Agent or Firm: Martin & Ferraro, LLP
Parent Case Text
CROSS REFERENCES TO RELATED APPLICATIONS
This application is a continuation-in-part of .[.pending.].
application Ser. No. .[.08,835,350: "Electromagnetically Shielded
Hearing Aid".]. .Iadd.08/835,350, filed Apr. 7, 1997, now U.S. Pat.
No. 6,031,923, which is a continuation-in-part of application Ser.
No. 08/557,999, filed Nov. 13, 1995, now U.S. Pat. No.
5,640,457.Iaddend..
Claims
What is claimed is
1. .[.An In The Ear, All in The Ear, In The Canal or Completely In
The Canal.]. .Iadd.A .Iaddend.hearing aid comprising: a case,
internal components, .[.a battery door, a battery, a microphone, a
speaker a volume control, a telephone coil activation switch, a
telephone coil, and internal wires;.]. .Iadd.and electrical
connections between the internal components, the hearing aid
including: means for making at least one of .Iaddend.the
.[.internal wires are made.]. .Iadd.electrical connections and the
internal components .Iaddend.resistant to electromagnetic
interference produced by cellular telephones in the 800 MHz to 100
GHz frequency range .[.by lining the case with an electrically
conductive material.].; one or more inductors or ferrite devices
.[.are put.]. in series with .[.some.]. .Iadd.at least one
.Iaddend.of the .[.internal wires.]. .Iadd.electrical connections
.Iaddend.or .Iadd.at least one of the internal .Iaddend.components;
one or more capacitors .[.are put.]. in parallel with .[.some.].
.Iadd.at least one .Iaddend.of the .[.internal wires.].
.Iadd.electrical connections .Iaddend.or .Iadd.at least one of the
internal .Iaddend.components; .Iadd.electrically conductive means
for shielding at least one of .Iaddend.the internal components
.[.arc shielded.]. .Iadd.or the electrical connections
.Iaddend.from electromagnetic interference .[.with electrically
conductive foil, and conductive gaskets;.]. .Iadd.produced by
cellular telephones.Iaddend.; the case of the hearing aid further
comprising a face plate and .Iadd.a .Iaddend.shell, .[.said.].
.Iadd.the .Iaddend.face plate and shell being made of or covered by
an electrically conductive material, .[.said.]. .Iadd.the
.Iaddend.face plate and shell being bonded together both
electrically and mechanically in such a way that none of the
conductive material comes in contact with the ear when the hearing
aid is worn, .[.and.]. .[.said.]. .Iadd.the .Iaddend.face plate
having .[.said.]. .Iadd.a .Iaddend.battery door made entirely or
partially of conductive material, .[.and.]. .[.said.]. .Iadd.the
.Iaddend.battery door being covered by a disposable strip of
conductive tape, and .[.said.]. .Iadd.the .Iaddend.conductive tape
having a conductive adhesive.
.Iadd.2. A hearing aid comprising: a microphone adapted to convert
a first acoustical sound into an electrical signal; a circuit
adapted to amplify the electrical signal into an amplified
electrical signal; a speaker adapted to convert the amplified
electrical signal into a second acoustical sound; a low-pass
electrical filter adapted to limit interference from interference
signals from a personal communication device with at least one of
the electrical signal and the amplified electrical signal so that
the second acoustical sound corresponds to the first acoustical
sound, said low-pass electrical filter comprising a capacitive
component electrically coupled from between said microphone and
said speaker to a ground and an inductive component electrically
coupled between said microphone and said speaker; a case made at
least in part of an electrically conductive material, said case
adapted to hold and protect internal components of the hearing aid,
said internal components including said microphone, said circuit
adapted to amplify, and said speaker; and at least one electrically
conductive shield shielding at least one of said internal
components from interference signals from the personal
communication device, said at least one electrically conductive
shield being at least one of an electrically conductive coating of
said case and an electrically conductive material lining said case.
.Iaddend.
.Iadd.3. The hearing aid of claim 2, wherein the electrical filter
limits interference from the interference signals having a
frequency of at least 800 MHz. .Iaddend.
.Iadd.4. The hearing aid of claim 2, wherein said capacitive
component of said low-pass electrical filter is adapted to bypass
interference signals from the personal communication device to the
ground and said inductive component of said low-pass electrical
filter is adapted to inhibit interference signals from the personal
communication device from passing between said microphone and said
speaker. .Iaddend.
.Iadd.5. The hearing aid of claim 2, wherein said case is one of
configured to be positioned behind an ear, in the ear, completely
in the ear, in an ear canal, and completely in the ear canal.
.Iaddend.
.Iadd.6. The hearing aid of claim 2, wherein said at least one
electrically conductive shield comprises an electrically conductive
foil. .Iaddend.
.Iadd.7. A hearing aid comprising: a microphone adapted to input a
first acoustical sound; a circuit adapted to amplify; a speaker
adapted to output a second acoustical sound; a first electrical
connection for transferring electrical signals from said microphone
to said circuit adapted to amplify; a second electrical connection
for transferring electrical signals from said circuit adapted to
amplify to said speaker; a low-pass electrical filter electrically
coupled to one of said first electrical connection and said second
electrical connection, said electrical filter adapted to attenuate
interference signals from a personal communication device from
propagating in one of said first electrical connection and said
second electrical connection so that the second acoustical sound
corresponds to the first acoustical sound, said low-pass electrical
filter comprising at least one capacitive component electrically
coupled to a ground and one of said first electrical connection and
said second electrical connection, and at least one inductive
component electrically coupled to the other of said first
electrical connection and said second electrical connection between
said microphone and said speaker; a case made at least in part of
an electrically conductive material to limit propagation of
interference signals from the personal communication device in at
least said first electrical connection and said second electrical
connection, said case being adapted to hold internal components of
the hearing aid; and at least one electrically conductive shield
shielding at least one internal component of the hearing aid, said
at least one internal component including one of said microphone,
said circuit adapted to amplify, and said speaker, said at least
one electrically conductive shield being at least one of an
electrically conductive coating of said case and an electrically
conductive material lining said case. .Iaddend.
.Iadd.8. The hearing aid of claim 7, wherein said case is one of
configured to be positioned behind an ear, in the ear, completely
in the ear, in an ear canal, and completely in the ear canal.
.Iaddend.
.Iadd.9. The hearing aid of claim 7, wherein said at least one
electrically conductive shield comprises an electrically conductive
foil. .Iaddend.
.Iadd.10. A hearing aid comprising: a microphone adapted to convert
a first acoustical sound into an electrical signal; a circuit
adapted to amplify the electrical signal into an amplified
electrical signal; a speaker adapted to convert the amplified
electrical signal into a second acoustical sound; a first
electrical connection between said microphone and said circuit
adapted to amplify; a second electrical connection between said
circuit adapted to amplify and said speaker; a low-pass electrical
filter electrically coupled to one of said first electrical
connection and said second electrical connection, said electrical
filter including a capacitive component and an inductive component
to limit interference from interference signals from a personal
communication device with one of the electrical signal and the
amplified electrical signal so that the second acoustical sound is
an audible reproduction of the first acoustical sound, said
inductive component being electrically coupled in series with at
least one of said microphone and said speaker, and said capacitive
component being electrically coupled in parallel with at least one
of said microphone and said speaker; a case made at least in part
of an electrically conductive material to limit propagation of
interference signals from the personal communication device in at
least said first electrical connection and said second electrical
connection, said case being adapted to hold internal components of
the hearing aid; and at least one electrically conductive shield
shielding at least one internal component of the hearing aid, said
at least one internal component including one of said microphone,
said circuit adapted to amplify, and said speaker, said at least
one electrically conductive shield being at least one of an
electrically conductive coating of said case and an electrically
conductive material lining said case. .Iaddend.
.Iadd.11. The hearing aid of claim 10, wherein said case is one of
configured to be positioned behind an ear, in the ear, completely
in the ear, in an ear canal, and completely in the ear canal.
.Iaddend.
.Iadd.12. The hearing aid of claim 10, wherein said at least one
electrically conductive shield comprises an electrically conductive
foil. .Iaddend.
Description
REFERENCE TO "MICROFICHE APPENDIX"
None
This invention was not made under any Federally sponsored research
and development program.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to hearing aids, and specifically to Behind
The Ear, In The Ear, In The Canal, or Completely In The Canal
hearing aids which are being shielded to be resistant to
electromagnetic interference produced by cellular telephones and
other devices in the 800 MHz to 100 GHz frequency range.
2. Description of Related Art
The invention consists of the following: hearing aids which can be
worn behind the ear, in the ear, or in the ear canal. These devices
are widely known in the hearing aid industry as follows: Behind The
Ear (BTE), In The Ear or All In The Ear (ITE), In The Canal (ITC),
and Completely In The Canal (CIC).
This invention intends to shield these types of hearing aids from
electromagnetic interference caused by cellular telephones in the
800 MHz-100 GHz frequency range by using an electrically conductive
foil to shield the circuitry components. Furthermore, an
electrically conductive gasket, paint or plastic could also be used
to shield the circuitry components.
Also, a filtering circuit composed of inductors and capacitors is
used to shield the circuitry components wherein ferrite beads or
ferrite toroids are used as the inductors.
Also, a case consisting of a faceplate and a shell, the shell being
made to fit in the ear, partially in the ear canal, or completely
in the ear canal, and made wholly or partially of an electrically
conductive material, the outside of which consists of a material
such as an acrylic that produces no adverse affects when worn in
the ear by most people.
The following devices are related to, but do not comprise any part
of this invention: hearing aids worn elsewhere on the body other
than in or behind the ear, known as "Body Aids", aids which
intentionally use an electric field antenna or a plane wave
antenna, hearing aids which couple sound waves through the bones of
the head, known as "Bone Conduction" hearing aids, and also hearing
aids which are built into eyeglass frames, and any devices which
require surgery to install, such as Cochlear Implants.
DESCRIPTION OF PRIOR ART
FIG. 5 (Prior Art) Illustrates the elements which comprise a
hearing aid. A Behind The Ear hearing aid is used for the
illustration, but the same components are found in other hearing
aids wherein the only difference could be the shape or size.
FIG. 5 (Prior Art) shows a hearing aid consists of an outer case 1,
usually made of plastic such as Lucite (Poly Methyl Methacrylate),
Non-Toxic Lucite, Poly Ethyl Methacrylate, Poly Vinyl Chloride,
Silicone, or Polyethylene.
The case 1 houses and protects the internal circuitry components.
The hearing aid has a battery door 3 which can be opened to replace
the battery, an opening for a microphone 5, an opening for the
speaker or receiver 6, and an opening for the volume control knob
7. The case 1 often has switches and controls, such as an optional
telecoil pickup switch which couples the hearing aid
electromagnetically to a telephone handset. The internal components
2 also consist of amplifiers and signal conditioning circuits as
shown in the block diagram. These circuits contain non linear
elements such as transistors. Some of the internal components are
coupled by fine internal wires 10.
Besides all these openings as disclosed above, In The Ear, In The
Canal, or Completely In The Canal hearing aids have a vent hole
(not shown) to prevent the buildup of air pressure and moisture in
the ear canal. This vent hole goes completely through the hearing
aid. To build an effective hearing aid, one requires several
openings due to current technology. Today's hearing aid users are
adversely affected by radio signals that are produced by cellular
telephones and other devices in the 800 MHz to 100 GHz frequency
range. These signals are often pulse modulated at rates of 200 Hz
to 300 Hz. Conventional hearing aids can unintentionally act as
radio receivers, with their internal wires 10 acting as
unintentional antennas, and their nonlinear elements
unintentionally acting as detection and demodulating circuits. This
causes the hearing aid to produce annoying or intolerable sounds,
such as a 200 Hz to 300 Hz hum.
Shapiro (U.S. Pat. No. 2,327,320) teaches a body-hearing aid with a
shield against electromagnetic interference which undoubtedly is
only effective for low frequency sources of electromagnetic
interference such as motors, hair dryers, and possibly fluorescent
lights. It should be noted that this shield would not be effective
against the current ultra-high frequency signals being experienced
by today's hearing aid users. Ferrite beads and transistors were
not available at this time and therefore, current circuitry
components can not be shielded by the methods disclosed by
Shapiro.
SUMMARY OF THE INVENTION
The invention consists of the following hearing aids which can be
worn behind the ear, in the ear, or in the ear canal, these devices
are widely known in the hearing aid industry as follows: Behind The
Ear (BTE), In The Ear or All In The Ear (ITE), In The Canal (ITC),
and Completely In The Canal (CIC). In this document, the phrase
"hearing aid worn in the ear" refers to ITE, ITC, and CIC hearing
aids.
This invention intends to shield these types of hearing aids from
electromagnetic interference caused by cellular telephones in the
800 MHz-100 GHz frequency range by using an electrically conductive
foil to shield the circuitry components. Furthermore, an
electrically conductive gasket, paint or plastic could also be used
to shield the circuitry components.
Also, a filtering circuit composed of inductors and capacitors is
used to shield the circuitry components wherein ferrite beads or
ferrite toroids are used as the inductors.
Also, a hearing aid worn in the ear consisting of a face plate and
a shell, each made wholly or partly of a conductive material, and
made in such a way that none of the conductive material comes in
contact with the ear when the hearing aid is worn.
DESCRIPTION OF THE DRAWINGS
FIG. 1 (Prior Art) shows a Behind The Ear hearing aid 1 and 2, an
In The Ear hearing aid 4, In The Canal hearing aids 5 & 6 and a
miniature ferrite bead 3 which can be used in this invention. The
Completely In The Canal hearing aid is not shown.
FIG. 2 shows how electromagnetic interference is transmitted by a
cellular telephone, is received by an internal wire of the hearing
aid which acts as an unintentional antenna, is detected and
demodulated by a nonlinear element of the hearing aid (for example,
a transistor), and results in a loud, audible signal which is
annoying or intolerable to the hearing aid wearer.
FIG. 3 Shows how the electromagnetic interference can be reduced or
eliminated by adding one or more inductors in series with the
internal wire which acts as an unintentional antenna. Ferrite beads
can also be used in place of the inductors shown.
FIG. 4 shows how the electromagnetic interference can be reduced or
eliminated by adding one or more capacitors in parallel with the
internal wire which acts as an unintentional antenna.
FIG. 5. (Prior Art) mechanically and schematically illustrates the
elements which comprise a hearing aid. A Behind The Ear hearing aid
is used for the illustration, but the same elements apply to In The
Ear, In The Canal, and Completely In The Canal hearing aids, the
only difference being one of size and shape.
FIG. 6 (Prior Art) Illustrates various ways in which inductors and
capacitors can be arranged to form low-pass filters. Ferrite beads
can be used in place of the inductors shown.
FIG. 7 describes the invention.
FIG. 8 shows the details of an electromagnetically shielded In The
Ear hearing aid consisting of a face plate 81 and a shell 85.
FIG. 9 shows the face plate 91 and the shell 95 after final
assembly.
DETAILED DESCRIPTION
The invention, shown in FIGS. 7, 8 and 9 consists of the following
elements: an outer case 11, which holds and protects the internal
components 12 and is shielded by one or more of the following: 11a:
Painting the case with a conductive coating, usually a paint which
is filled with silver, nickel, or copper, such as the following
products made by Chomerics, Inc. of Woburn Massachusetts:
"Cho-Shield 596" or "Cho-Flex 601." 11b: Lining the case with an
electrically conductive material such as conductive foil, usually
copper or aluminum foil, such as "Cho-foil" produced by Chomerics,
Inc. 11c. Making the case out of a conductive material, such as a
plastic which has been impregnated with metal or carbon. 11d. Using
conductive gaskets such as "CHO-seal 1215" made by Chomerics,
Inc.
The outer case 11 houses the internal components 12 which must
sometimes be shielded in addition to the case. The techniques used
to shield the internal components 12 are those described in 11a,
11b, 11c, and 11d above.
The internal components 12 of the hearing aid must also be
sometimes modified so that the 800 MHz-100 GHz radio signals
produced by cellular telephones and other devices cannot pass
effectively from one component to another. This is done in such a
way that the normal functions of the hearing aid are not adversely
affected. Some or all of the following techniques are employed:
12a: The addition of one or more inductors 13 in series. FIG. 2
depicts a pulse modulated radio signal such as those produced by
some cellular telephones. This signal is unintentionally picked up
by an internal wire, acting as an unintentional antenna. The signal
is then demodulated and detected by one of the nonlinear elements
of the hearing aid, such as the audio amplifier. As shown in FIG.
3, by adding one or more inductors in series with the unintentional
antenna, the incoming radio signal is blocked by the high impedance
of the inductors. The inductors present a low impedance to the
intended audio signals, which pass through intact. 12b: The
Addition of Ferrite beads 14: Ferrite beads, such as model
#2673008501 made by Fair-Rite Inc. of Wallkill, N.Y. and depicted
as item #3 in FIG. 1, when slipped over an internal wire
effectively add an inductor in series as described in 12a above.
Other shapes of the Ferrite material, such as toroids, rods, and
custom molded shapes may be used. 12c: The addition of one or more
capacitors in parallel: As shown in FIG. 4, the addition of one or
more capacitors in parallel with the unintentional antenna has the
same de-coupling effect as the addition of inductors in series. In
this case, the capacitors present a very low impedance to the radio
signal, shorting it to ground.
The capacitors present a high impedance to the audio signals, which
pass through intact. 12d: Filtering: This consists of adding
combinations of inductors (including ferrites) and capacitors as
described in FIG. 6. 22: As shown in FIG. 8, an electromagnetically
shielded hearing aid worn in the ear, that is an ITE, ITC or CIC
hearing aid, consisting of a face plate 81 which may contain one or
more controls 82, a microphone opening 83, and a battery door 84;
and a shell 85, all made wholly or partially of an electrically
conductive material, the shell 85 being molded to fit in the ear,
or partially in the ear canal, or completely in the ear canal, and
the outside of which is made of or covered by a material such as
acrylic, which produces no adverse effects when worn in the ear by
most people.
The face plate 81 is also made wholly or partially of an
electrically conductive material, or covered by a conductive
material, and its perimeter is cut so as to be congruent with the
perimeter 86 of the opening of the shell, and to fit over it
forming the case of the hearing aid as shown in FIG. 9.
The face plate 81 and the shell 85 are bonded mechanically and
their conductive surfaces are bonded electrically. This can be done
by using an electrically conductive adhesive, or any combination of
conductive and non-conductive adhesives and one or more conductive
gaskets. To prevent allergic reactions or other adverse effects,
the electrical bonding is done in such a way that neither the
conductive adhesive nor the conductive gasket will come in contact
with the ear when the hearing aid is properly worn. One way to
accomplish this is to cover the inside of the shell with conductive
paint. This paint will also cover the perimeter 86 of the shell's
opening. A conductive adhesive is applied to this perimeter, and
the conductive part of the face plate is attached on top of this
conductive perimeter. When the adhesive hardens, the conductive
perimeter is buffed to a smooth finish.
If any conductive material remains accessible to the ear, it will
be covered by a coating of a material such as acrylic, which
produces no adverse effects when worn in the ear by most people.
The face plate, most of which does not come in contact with the
ear, can be made entirely of a conductive material or also coated
with a material which produces no adverse effects when worn in the
ear by most people.
Because the door of battery compartment can be a major opening
through which radio signals can leak in, the door must be made
partially or completely of a conductive material, and designed in
such a way as to provide an electrical bond with the face plate.
One way to do this is to design the door to be a threaded cap, like
the top of a thermos bottle. Another way is to design the door to
completely cover the opening, like the lid of a toilet seat, and
using a conductive gasket to provide an effective electromagnetic
shield.
Yet another way is to use a standard hearing aid battery door, and
to cover it with a disposable strip of conductive tape which uses a
conductive adhesive. For cosmetic reasons, the surface of this
conductive tape can be dyed or painted to match the color of the
hearing aid.
Hearing aids range from simple audio amplifiers to complex devices
employing digital signal processing techniques. Each design
presents a slightly different problem and some or all of the above
protection techniques will be used. Because of the many openings
that a hearing aid must have, it is impossible to shield its outer
case 11 completely. The high field strengths and Ultra-High
Frequencies produced by cellular telephones may require a
combination of the above techniques.
The preferred embodiments are described in claims 1 and 4.
The resultant hearing aid will be unaffected by the radio signals
produced by cellular telephones, allowing hearing impaired people
to take advantage of cellular telephones and other personal
communication devices while wearing their hearing aids.
* * * * *