An audiocoil is an inductive pick-up coil used to sense the changing magnetic fields associated with telephone receivers. Audiocoil-enabled hearing aids allow users to listen to telephones without experiencing acoustic feedback. Instead of using a microphone to detect the sound produced by a telephone, an audiocoil-enabled hearing aid detects the magnetic field generated by the telephone handset. This signal is then transformed into amplified sound using the circuitry and miniature speaker in the hearing aid.
Audiocoils can also be used to couple hearing aids inductively to assistive listening devices such loop transmitters (personal and/or room-based).
Audiocoils are also known as telecoils.