Acoustics – Anatomic or prosthetic relation – Ear and mouth
Reexamination Certificate
2000-10-23
2003-07-01
Nappi, Robert E. (Department: 2837)
Acoustics
Anatomic or prosthetic relation
Ear and mouth
C181S129000, C181S130000, C381S312000, C381S322000, C381S324000, C381S325000, C381S328000
Reexamination Certificate
active
06585075
ABSTRACT:
TECHNICAL FIELD
The present invention relates, in general, to hearing aids and, in particular, to a hearing aid having a speaker that is mounted rigidly to the hearing aid housing and an energy absorbing tip that absorbs mechanical and acoustic energy from the speaker that might otherwise create undesired feedback.
BACKGROUND OF THE INVENTION
FIG. 1
is a schematic sectional view of a conventional hearing aid. This hearing aid includes a housing
10
having a sound inlet
12
extending through a faceplate
13
of the housing and through which outside sound reaches a microphone
14
. The microphone develops an electrical signal representative of the outside sound and the microphone signal is conducted to an amplifier
16
that amplifies the microphone signal. Amplifier
16
is powered by a battery
18
that is held in a battery holder
20
mounted for pivotal movement about a hinge
22
on housing
10
. Battery holder
20
is held in place by a battery snap
24
on housing
10
.
The amplified microphone signal is conducted to a speaker
26
, commonly referred to as a receiver when used in a hearing aid, that develops an audio output of the amplified microphone signal. The audio output is conducted through a speaker sound outlet
28
and a housing outlet
30
, defined by a tube
32
, into the ear canal of the person wearing the hearing aid.
Speaker
26
is held in a resilient suspension
34
that is mounted to housing
10
by tube
32
. Tube
32
is generally flexible but is sufficiently stiff to support resilient suspension
34
. As shown in
FIG. 1
, resilient suspension
34
is spaced from housing
10
by spaces
36
and
38
that surround the resilient suspension. Resilient suspension
34
, tube
32
and spaces
36
and
38
serve to isolate vibrations generated by speaker
26
when the speaker is driven to create the audio output.
One of the constraints of existing hearing aid designs, such as the one shown in
FIG. 1
, is that of internal feedback. A hearing aid is designed with: (a) a microphone that picks up sound and converts the sound to an electrical signal, (b) an amplifier that amplifies the microphone electrical signal, and (c) a speaker that converts the amplified microphone electrical signal back to sound energy.
Internal feedback occurs when the sound energy generated by the speaker reaches the microphone at an intensity greater than that of the sound that was originally picked up by the microphone. The feedback path can be acoustic or mechanical or both acoustic and mechanical.
Acoustic feedback is most often the result of sound generated by speaker
26
passing through tube
32
and into housing
10
and finding a path through faceplate
13
back to microphone inlet
14
. Because most hearing aid batteries require air to generate electricity, faceplate
13
is designed with openings that allow air to pass through and, as a consequence, sound also can pass through.
Mechanical feedback occurs because speaker
26
vibrates as it produces sound. These vibrations can travel through tube
32
to housing
10
or through resilient suspension
34
to housing
10
when the resilient suspension is in contact with the housing. In practice, it is difficult to maintain spaces
36
and
38
between resilient suspension
34
and housing
10
. The designers of hearing aids strive to make hearing aids as small as possible so that the hearing aids can fit into the ear as far as possible. The mechanical vibrations conducted from resilient suspension
34
to housing
10
travel though the walls of the housing and ultimately cause a microphone
14
to vibrate. Movement of the diaphragm of microphone
14
relative to the wall of housing
10
causes microphone
14
to generate an electrical signal. Although designed to minimize the effect of such vibrations, microphone
14
cannot differentiate whether a movement is mechanical or acoustic.
Mechanical/acoustic feedback occurs when vibrations of speaker
26
cause vibration in housing
10
. Some of these vibrations, in turn, generate sound energy that is picked up by microphone
14
.
Selection of appropriate materials for tube
32
and resilient suspension
34
is important to prevent feedback. High durometer materials are good sound containers but transmit mechanical energy. Low durometer materials can isolate vibrations. However, low durometer materials are poor sound containers. If resilient suspension
34
makes contact with housing
10
, mechanical energy can pass through. A thicker suspension helps but adds size. Allowing a greater space between resilient suspension
34
and housing
10
helps but also adds size. The designers of hearing aids constantly are faced with tradeoffs between physical size of the hearing aid and amplification by the hearing aid.
SUMMARY OF THE INVENTION
A hearing aid, constructed in accordance with the present invention, includes a housing having a sound inlet through which an outside sound enters the housing and a sound outlet through which an amplified version of the outside sound exits the housing. This hearing aid also has a battery within the housing and a microphone within the housing responsive to the outside sound entering the housing through the sound inlet for developing an electrical signal representative of the outside sound entering the housing. A hearing aid, constructed in accordance with the present invention, further includes an amplifier powered by the battery and responsive to the electrical signal for developing an amplified version of the electrical signal, an energy absorbing tip, and a speaker surrounded by the energy absorbing tip, responsive to the amplified version of the electrical signal for developing and conducting to the sound outlet the amplified version of the outside sound entering the housing, and rigidly mounted to the housing to channel acoustic energy and mechanical energy generated by the speaker to the energy absorbing tip.
According to another aspect of the present invention, the open end of the sound outlet from which sound emanates is remote from that end of the hearing aid that is innermost in the ear and closest to the ear canal of the person wearing the hearing aid.
REFERENCES:
patent: 3374318 (1968-03-01), Martin
patent: 3448224 (1969-06-01), Giller
patent: 3852540 (1974-12-01), Diethelm
patent: 4375016 (1983-02-01), Harada
patent: 4532649 (1985-07-01), Bellafiore
patent: 4553627 (1985-11-01), Gastmeier et al.
patent: 4584437 (1986-04-01), Giannetti
patent: 4706778 (1987-11-01), Topholm
patent: 4739512 (1988-04-01), Hartl et al.
patent: 4870689 (1989-09-01), Weiss
patent: 4937876 (1990-06-01), Biermans
patent: 4962537 (1990-10-01), Basel
patent: 4969534 (1990-11-01), Kolpe et al.
patent: 5166659 (1992-11-01), Navarro
patent: 5742692 (1998-04-01), Garcia et al.
patent: 5748743 (1998-05-01), Weeks
patent: 6144749 (2000-11-01), Fideler
patent: 6212283 (2001-04-01), Fletcher et al.
patent: 6310961 (2001-10-01), Oliveira et al.
Miller Patrick
Nappi Robert E.
RatnerPrestia
LandOfFree
Hearing aid having hard mounted speaker and energy absorbing... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Hearing aid having hard mounted speaker and energy absorbing..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Hearing aid having hard mounted speaker and energy absorbing... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3067137