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HOW HEARING AIDS
WORK
A hearing aid amplifies and processes sound in much the same way that a
stereo sound system does. However it is much more complex, because all of the
technology has to fit into a tiny device that can sit in, or on, the ear.
A hearing aid consists of three major components, all protected by a plastic
case which can be fitted on or in the ear.
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The first component is a microphone, which changes sound in the air into
an electrical signal.
The second component is an amplifier. The amplifier increases the
intensity of the electrical signal. Amplifiers also use filters, which have
the ability to selectively modify sound, so only the sound needed by the
person with the hearing loss is amplified. Some filters can filter out
unwanted noise.
The third component is a speaker. The speaker changes the electrical
signal which has been amplified and filtered back into an acoustic
signal which the wearer hears. The person wearing the aid can adjust the
volume for clarity of the sound.
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The cost of a hearing aid is relatively high, due to the fact that the
components have to be miniaturised. Imagine the complexity of having to make
speakers and microphones which are small enough to fit into a custom made case which
is small enough to fit on or in the ear.
Hearing aids require special batteries, which are extremely small. These
batteries may last from a few days to a few weeks, depending on the type of
hearing aid and the amount of time used.
Hearing aids need very little special care. They are built to be durable, but
like any other electronic device, they can be broken when dropped. Water can
also cause damage. Ear wax can plug the opening for sound in the ear mold. Wax
should be washed from the ear regularly. Ear wax guards, which can be put on the
hearing aid, is also available.
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