AFILS - Audio Frequency Induction Loop System - the most technically correct term.  More frequently used terms include audio
            loop, deaf loop, hearing loop, hearing assistance loop, induction loop, inductive hearing loop or magnetic induction
            hearing assistance loop

Hearing aid - an assistive hearing device prescribed by an audiologist (after an appropriate hearing test!) to improve hearing
Loop - the "antenna" that carries the sound signal produced by the Loop Amplifier

    Couch/Sofa loop - a small loop that encircles a couch or sofa so that anyone sitting on it can hear via the loop
    Counter loop - a small loop set up at a store, bank or ticket counter to enable dialogue between the hard of hearing
                            customer and the teller or cashier
    Pillow loop - a pad that acts as a loop for the person seated on it

Loop Amplifier - an electronic device used to strengthen the sound source (e.g. computer, microphone, radio, tv) to the
                           level required for the loop system to be "heard" by the hearing aid "T" coil

Telecoil (T coil) -  a tiny coil of wire inside the hearing aid that  "hears" the electrically produced magnetic sound signal in a loop or
                             telephone earpiece.  More about the telecoil …