AFILS. Audio Frequency
Induction Loop Systems for the hearing impaired.
What is a loop system and how
does it work?
Loop systems are used by hearing-aid
users to overcome acoustic difficulties in certain situations. When
a user is close to the person talking in a small, quiet, acoustically
favourable room they can use the aid's internal microphone without problems.
But in a large, noisy or reverberant room, or, when speaking to a teller
behind a glass screen it can be difficult to hear what is being said.
A loop system consists of a cable
installed around the room connected via an amplifier to one or more
sources of sound signals. The loop amplifier produces an audio frequency
electric current in the induction loop cable, causing a magnetic field
to be produced. Most hearing aids have a switch marked M and T. The
M (microphone) position is for "normal" listening. The T (telecoil)
position is for receiving the sound via the induction coil built into
the hearing aid.