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Specialized Services >> Hearing Aids
Hearing Aids
A hearing aid is an Electroacoustic device which typically fits in or
behind the wearer's ear, and is designed to amplify and
adjust sounds in
order to help a hard-of-hearing person hear sounds more clearly.
There are thousands of hearing aids models. All of them include a microphone (to pick up sound),
amplifier (to boost sound strength), a receiver or speaker (to deliver
sound to the ear), and are powered by a battery. Depending on the
technology, it is possible to add features to filter background noise,
reduce feedback, lower sound in noisy settings, etc.
In
general, hearing aid styles are divided into behind the ear (B.T.E) and
custom (in the ear or (I.T.E)).
In-the-ear (ITE) hearing aid:
Fits completely in the ear and or outer ear canal. This is a popular
style for adult hearing aid users but there are disadvantage for
children using them. They cannot be used with FM systems and usually cannot be used with other listening devices.
Also, young children's ears are continually growing which results in
the need for frequent re-casing and re-shelling of the hearing aids.
While this is being done, the child is usually left without amplification
for a few days. This size of hearing aid is not powerful enough to
provide adequate amplification for severe or profound hearing
loss.
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Behind-the-ear (BTE) hearing aid:
Sits behind the ear. Amplified sound is sent to the ear through tubing
and an ear mold
(piece of silicon or other soft material molded to exactly fit in the
ear and to deliver the sound from the hearing aid. These hearing aids can provide the amplification necessary
for all degrees of hearing loss including profound. They don’t require
as much maintenance as the ITE hearing aids and are easily
interchangeable if they need to be serviced. Also they are easier to
handle and tend to be more reliable. They can be attached to other
special listening devices such as FM systems. Because the electronics
are behind the ear and not in the actual ear canal, they are considered to
be useful for those with chronic ear infections or for those who
produce a large amount of ear wax.
Open Fit hearing aid:
Similar to the (B.T.E) but smaller in size and the tubing is slim with
a small flexible tip that sits in the ear canal. The small tip in the
ear results in an open fit without 'plugging' the ears. An open fit
hearing aid usually results in a more comfortable fit, a more natural
sound, and can eliminate problems with the patient’s own voice.
However, they are not suitable for severe hearing losses.
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On-the-body
aids
On-the-body
Aids feature a larger microphone, amplifier, and power supply inside a
case carried inside the pocket, or attached to clothing. The receiver
attaches directly to the ear mold; its power comes through a flexible
wire from the amplifier. Although larger than other aids, the
on-the-body aids are more powerful and easier to adjust than other
devices. While not popular for everyone, they are often used by those
with a profound hearing loss, or by very young children. Some people
who are almost totally deaf find they need the extra power boost
available only from a body aid.
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Eyeglass
Eyeglass models are the same as behind-the-ear devices, except that the
case fits into an eyeglass frame instead of resting behind the ears.
Not many people buy this type of aid, but those who do believe it's
less obvious, although there is a tube that travels from the temple of
the glasses to the ear mold. But it can be hard to fit this type of
aid, and repairs can be problematic. Also, if the aid breaks, the
person also loses the benefit of the glasses.
CROS (Contralateral
Routing of Signal):
This hearing aid system is designed for people with unilateral hearing
loss (CROS) or for hearing losses which are much more severe in one ear
than the other (BI-CROS). A microphone is placed on the poorer ear and
the signal is routed to a hearing aid on the better ear. This provides
sound from the weak side.
FM Systems:
These are assistive listening devices used to improve the
signal-to-noise ratio for the listener and to reduce the effects of
poor acoustics. The microphone is placed near the sound source -
usually the speaker's mouth but can be a television, radio, etc. - and
a receiver for the listener. The receiver can be a separate module with
headphones, or it can be a miniature piece attached to a BTE hearing
aid, and some FM receivers are now being integrated directly into
hearing aids. The listener is able to hear the speaker above the
background noise at considerable distances. There are no wires
connecting the listener to the speaker which gives mobility to both.
These units are often of benefit for classes, lectures, conferences,
meetings, in restaurants and in large groups.
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BAHA (Bone Anchored Hearing Aid):
This device combines a sound processor with a small titanium fixture
implanted behind the ear. The system allows sound to be conducted
through the bone rather than via the middle ear – a process known as
direct bone conduction. The surgery is minor, and many patients report
a wide range of advantages over other hearing devices. BAHA is used
with people with chronic ear infections, congenital hearing loss and
single-sided deafness.
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