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Glossary of Hearing Aid Users

ODHHS Information and Technical Assistance Series

Glossary for Hearing Aid Users
(Source: American Speech-Language-Hearing Association, ASHA)

Components of a Hearing Aid

A hearing aid contains four components:
  1. Microphone: changes acoustic (sound) signals into electrical signals.
  2. Amplifier: increases the intensity (or loudness) of the electrical signal.
  3. Receiver: changes the amplified electrical signal back into an amplified sound signal.
  4. Battery: the power source for the electrical circuits.

Amplified sound is then delivered into the ear through either an earhook, tube, earmold or a shell into the ear canal.
  • Earhook: extension of behind-the-ear (BTE) hearing aid that conducts amplified sound from the hearing aid to the tubing, which in turn channels the amplified sound to the earmold.
  • Tubing: plastic material of a specified size that channels and directs sound in hearing aid systems.
  • Earmold: a cast of the outer part of the ear that funnels sound into the ear and is attached to a hearing aid.

Hearing Aid Controls

Each hearing aid includes one or more controls for purposes of adjusting loudness input and output and for selecting the frequency emphasis of the hearing aid. This flexibility allows the audiologist to "custom fit" the hearing aid to your specific hearing needs. A volume (gain) control can be adjusted by the hearing aid user. Other hearing aid controls are manipulated by screwdriver controls.
  • Gain: amount of amplification; measured in decibels (dB).
  • Volume Control: a control for changing the amplification level of sound. This control is usually set so that most incoming sounds are heard at a comfortable loudness level. However, the volume control can be adjusted for different listening situations.
  • Output Range: fixes the minimum to maximum decibel levels of the receiver of the hearing aid when sound entering the aid varies widely in intensity. An output control is adjusted by an audiologist so that sound coming out of the aid stays below a users discomfort threshold. Output ranges vary among hearing aids.
  • Microphone-Telecoil Switch: a two-position hearing aid control for changing from microphone input of sound signal to corresponding telecoil input of the signal; for use with compatible telephone receivers and some special listening systems. (see telecoil below).
  • Telecoil: circuitry that allows the hearing aid to accept sound conveyed by magnetic signals (as from a telephone receiver and other special listening systems). Such sound is free from acoustic feedback and background noise. A telecoil can be built into a behind-the-ear (BTE) aid, or an in-the-ear (ITE) aid. An in-the-canal (ITC) aid user may find an amplified handset or other telephone modification useful.
  • Direct Audio Input (DAI): allows direct connection of the hearing aid to a telephone handset, radio, TV, movie projector, stereo, or other special listening system.
  • Maximum Power Output: greatest adjustment of the low or high frequency (pitch) response of a hearing aid. The audiologist presets these controls to the specific hearing loss a client.
  • Noise Suppression: some hearing aids have circuitry designed to control unwanted background noise, for example, automatic gain control, compression amplification, automatic signal processing , and noise suppression switches. Some hearing aids are programmable and use digital technology to automatically adjust hearing aid settings for different listening environments.

The American Speech-Language-Hearing Association (ASHA) is the national professional and scientific society that represents 81,427 audiologists; speech-language pathologists; and speech, language and hearing scientists. ASHA's mission is to promote the interest of its members, to provide them with the highest quality services, and to advocate for people with communication disabilities. ASHA's Consumer Affairs Division provides an information and referral service on a broad range of speech, language and hearing disabilities for both children and adults.