The induction loop is a small cable that goes round the perimeter of a room or listening area and forms a loop. Both ends of the cable are connected to the output of a specialist design loop amplifier. A current from the loop amplifier powers the cable and the amplifier gets its signal from a direct sound source. This can be a microphone or a connection into a TV, PA system, laptop or DVD player.
The resulting electric current in the induction loop produces a magnetic field. The hearing aid user can pick up this field when they switch their hearing instrument to the T position. The user is then able to hear audible sound very clearly. Overspill may occur when a loop system is being used, whereby the signal from the loop reaches outside the loop area. This means that privacy cannot be guaranteed in a room where a loop is fitted.