hearing aid

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hearing aid,

device used in some forms of deafness to amplify sound before it reaches the auditory organs. Modern hearing aids are electronic. They contain a tiny receiver and a transistor amplifier, and are usually battery powered. Some are small enough to fit into an arm of a pair of eyeglasses, or into the outer ear. The bone-conduction hearing aid, placed behind the ear, channels sound waves to the adjacent bony part of the skull, which then transmits the vibrations to the auditory nerve of the cochlea. The air-conduction hearing aid amplifies sounds and directs them into the ear toward the tympanic membrane. In recent years, a number of advancements have been made to hearing aids, improving the comfort, sensitivity, and aesthetic quality of the devices. Today, many hearing aids are customized to amplify only those noises (e.g., high frequency) that the user has difficulty hearing. Cochlear implants have been developed for use by certain totally deaf people. They consist of mechanical replacements for ineffective hair cells in the inner ear, which transform sound vibrations into electronic impulses that stimulate the auditory nerve.

Hearing Aid


a sound-amplifying device used by persons afflicted with deafness or impaired hearing. The earliest hearing aids were purely acoustic devices, such as ear trumpets, whose narrow end was inserted into the ear. Modern hearing aids are electroacoustic devices consisting of a microphone, an amplifier, and an earphone. The sound enters the microphone, where it is converted into electric voltage. Amplified by electronic tubes or transistors, this voltage enters the earphone, where it is reconverted into amplified sound.

Hearing aids differ in design according to the nature of the auditory impairment. The standard earphone, inserted into the ear, transmits amplified sound into the external ear, and the bone conduction receiver, pressed against the mastoid process of the temporal bone, transmits sound into the inner ear.

Miniature hearing aids have a miniature earphone that is attached to an individually molded insert in the external ear. Some hearing aids are built into eyeglass frames or hair clips. Pocket hearing aids are manufactured as well. Hearing aids are prescribed by a physician and individually fitted in specialized laboratories after exhaustive hearing tests.

hearing aid

[′hir·iŋ ‚ād]
(engineering acoustics)
A miniature, portable sound amplifier for persons with impaired hearing, consisting of a microphone, audio amplifier, earphone, and battery.

hearing aid

a device for assisting the hearing of partially deaf people, typically consisting of a small battery-powered electronic amplifier with microphone and earphone, worn by a deaf person in or behind the ear
References in periodicals archive ?
The NHS mainly offers standard behind-the-ear hearing aids with a quite noticeable plastic earpiece.
FM systems can now also be built into personal hearing aids or be attached to behind-the-ear hearing aids via a 'boot', a miniature adapter.
Table 1: Potential Addressable Market for Cochlear Implants (In terms of Number of Cases of Profound and Severe Hearing Impairment in Developed and Developing World): 2005 II-3 Poor Levels of Hearing Aid Penetration Promise Bright Prospects II-3 Factors Influencing the Growth of Hearing Aids Market: II-4 Growth in Cosmetic, Behind-The-Ear Hearing Aids Market II-4 Binaural Fittings Market to Grow II-4
However, audiologists generally prefer behind-the-ear hearing aids for young children because they can be fine-tuned more easily as additional information about the child's hearing loss becomes available, or if a child's hearing changes over time.
GLOBAL MARKET OVERVIEW AND ANALYSIS II-1 Curtain Raiser II-1 Developed Markets Dominate Sales, Developing Countries Drive Momentum II-2 Hearing Aids - The Dominant Product Segment II-2 Volume Sales of Hearing Aids On a Positive Note II-3 Behind-the-ear Hearing Aids Corner Lion's Share of Global Hearing Aids Market II-4 Cochlear Implants - The Fastest Growing Product Segment II-4 Emerging Economies: Opportunities in Store II-5 Table 1: Healthcare Spending as a Percentage of GDP across Major Countries (2012) (includes corresponding Graph/Chart) II-6 2.