The first wearable electronic hearing aid was the body hearing aid. This type of
aid included a variably sized case that was worn on the body of the user and
contained the microphone, amplifier, battery, on/off switch, and volume control.
Leading from the case were the receiver cord and the receiver. Attached to the
receiver was an ear mold that was fitted to the wearer's ear.
Because of the size of the aid and the placement of the microphone on the body
rather than in the ear, very few body aids currently are dispensed.
The behind-the-ear hearing aid is worn behind the pinna.
The body of the instrument contains the microphone, amplifier, receiver,
on/off switch, and volume control. Leading from the receiver is
the ear hook, which loops around the ear and carries the amplified
sound to the tubing attached to the ear mold.
The behind-the-ear hearing aid was the most common aid dispensed
from the early 1960s until the early 1980s. However, since 1983,
the in-the-ear%u2013type hearing aids have captured the largest part of
the hearing aid market. In 1987, approximately 80% of hearing aids
dispensed in the United States were in-the-ear instruments;
most of the remaining hearing aids were behind-the-ear instruments.
A new thin tube variety of behind-the-ear hearing aid has taken up
approximately 17% of the total market in 2005. These behind-the-ear
aids are very small and are nearly invisible when fit behind the
ear. The longer thin tubing and fitting software allow access to
higher frequency amplification with increased bandwidth from
6000-8000 Hz. These open-fitting hearing aids provide excellent
sound quality and better directional microphone placement
compared with many in-the-ear hearing aids.
The in-the-ear hearing aids can be broken down into full-shell, half-shell,
canal, and completely in-the-canal instruments. Every in-the-ear instrument
contains its microphone, amplifier, and receiver. The faceplate of the
instrument includes the battery door, on/off switch, volume control
(if available), and microphone opening. Most of the shells for each
of these aids are made from ear mold impressions taken from the
individuals in whom these aids are to be fitted.
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