|A hearing aid is a small electronic device that amplifies
sound. No matter what style, size, or brand, all hearing aids have
the same basic components: a microphone, an amplifier, a receiver and a
battery. All the parts of a hearing aid work together to amplify
sound. The hearing aid has internal and external controls.
The internal controls are set by the audiologist based on the users frequency
needs and the external controls can be set by the user, such as the "on"
and "off" switch and volume control. Some hearing aid users depend on a
Telecoil switch to be able to use a telephone or an assistive listening
device, which can be controlled by the user.
The three basic sizes of hearing aids are the behind-the-ear,
in-the-ear, and in-the-canal. A behind-the-ear aid fits behind the
ear with a soft plastic ear mold which fits inside the ear. The plastic
tube, or ear hook is connected to the earmold and curves around the top
of the ear to attach to the microphone, battery, amplifier and receiver
that are all inside the case behind the ear.
Behind-the-ear is suitable for all ages and all degrees
of hearing loss. This aid is most powerful and therefore it is used
more with people who have a moderate to profound hearing loss. Unfortunately,
it is not as cosmetically appealing as the other two options.
In-the-ear hearing aid fits completely in the outer
ear. The hard earmold holds all the parts within its small case,
which means the microphone and receiver are close together increasing chances
of feedback. The in-the-ear hearing aid is not suitable for children
or for people with a profound hearing loss. Also, it can be easily
damaged by earwax and/or ear drainage; however, people prefer this aid
due to its size and it being cosmetically appealing.
In-the-canal hearing aid is similar
to the in-the-ear hearing aid, but it is extremely smaller because it fits
in the ear canal. There are two options for in-the-canal aid.
There is the in-the-canal aid which mainly fits in the ear canal or an
even smaller aid which fits completely in the canal and cannot be seen
by others. Both sizes are only suitable for mild to moderate hearing
loss because the chance of feedback is increased. The in-the-canal
aid has similar disadvantages to the in-the-ear aid, but one main obstacle
with in-the-canal aids is that the size of the aid does not allow easy
access to the volume control and hte battery door.
For more information:
aids and How they Work
Demystifying Assistive Listening Devices: The Devil is in the Detail