0 a wire inside a hearing aid that can help people hear better on the telephone, and that can receive sound signals sent from an induction loop (= an electronic system in a public place, for example a theatre, that sends such signals): --
Hearing Aid Loops use Induction Technology to transmit sound from a PA system directly to the individual’s hearing aid through the T-coil.
The telecoil works as an antenna to pick up magnetic signals and streams them as sound into your hearing aids.
A telecoil, a small device that can be embedded in the hearing aid, can improve hearing on the telephone.