: an electronic device usually worn in or behind the ear of a hearing-impaired person for amplifying sound
Device that increases the loudness of sounds in the user's ear. Its principal components are a microphone, an amplifier, and an earphone. Hearing aids are increasingly smaller and less conspicuous, fitting behind the earlobe or within the ear canal. They have widely differing characteristics, amplifying different components of speech sounds for maximum comprehension by each wearer. Hearing aids with automatic volume control vary the amplification automatically with the input.