This system transmits sound to a hearing aid's Telecoil via a magnetic field created by the induction loop. In this way only sound fed directly into the induction loop (through a microphone for example) will be picked up by hearing aid users using the "T" Position. (note not all hearing aids have this facility). Any number of people within the loop's field can receive the transmission; making it a low-maintenance, cost-effective solution.
Thought has to be given to the nature of information being transmitted by induction loops, as magnetic field overspill is almost inevitable, meaning that ‘eavesdropping’ is relatively easy whether on purpose or accidentally.
Types of Induction Loop Systems
• Counter Loops: the counter loop is designed to facilitate the communication between two people; a hearing person and a hard of hearing person at a fixed location. A wire loop is normally fixed out of sight to the underside surface of the desk or counter with adhesive or clips. The loop is connected to a small amplifier (typical size 216mm x 124mm x 44mm) which is powered from an adjacent standard 13A mains socket. A small microphone is normally fitted to the underside of the counter pointing towards the face of the operative working at the counter. Again, this is normally installed so it is not visible from the front (customer-facing) side of the counter. Ideally, the loop needs to be positioned away from computer screens and other electrical equipment that can cause a “hum” on the audio.
• Portable Loop: the portable loop is designed to facilitate the communication between two people; a hearing person and a hard of hearing person, but can be moved from location to location. It is a battery powered unit with a mains charger incorporating a microphone, amplifier and loop.
• Room Loops: the room loop is designed for a fixed location and will provide assistive listening for as many hearing aid wearing people that can fit in the room. The loop cable/tape can either be installed on the floor (typically underneath the carpet) or in the ceiling. It can also be run around the skirting board of a room, however special protection is required at door entrances. Connected to the loop will be a loop driver/amplifier (model determined by size of room) and a source of audio e.g. microphone / mixing desk.