Article
Article
Hearing aid
Article By:
Killion, Mead C. Etymotic Research, Elk Grove Village, Illinois.
Villchur, Edgar Foundation for Hearing Aid Research, Woodstock, New York.
Last reviewed:January 2020
DOI:https://doi.org/10.1036/1097-8542.309700
A device that amplifies sound for someone with a hearing loss. A typical aid consists of a microphone, an electronic amplifier, an earphone (called a receiver), and a battery. The sound is coupled to the ear with an earmold. The great majority of earmolds are cast from impressions of the individual patient's ear canal, but over-the-counter and mail-order hearing aids use prefabricated earmolds, commonly offered in several sizes. In the case of in-the-ear hearing aids, all components are small enough to be contained in an earmold shell that fits within the ear canal and concha, or even within the canal alone (Fig. 1). See also: Amplifier; Ear (vertebrate); Earphones; Microphone
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