Opus Technologies DCL20-65, Installation And User Manual

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5. Working principle
An induction loop is composed of a wire forming
a loop, connected to an audio amplifier. Hearing
aids are often equipped with a copper spiral
usually called "T" or "T-coil". The magnetic field
generated by the large loop will cross the coil
and, by the induction process, the electrical
signal present in the large loop will be found in
the one small. The signal of the au- dio amplifier
is transmitted to the hearing aids, which will
then restore it to the ear of the im- paired ones.
The loop can be installed in the floor or at the
roof level, more precisely between 1.10m and
2.20m from the listening height(ears).
The presence of an hearing loop is often indi-
cated by a blue logo representing a crossed out
ear and a letter T. Generally, a hearing aid has
two major positions, the M and the T. The posi-
tion M makes it possible to perceive the sound
thanks to sound pressure as a microphone, while
the position T (T for telephone) directly receives
the audio signals transmitted by induc- tion via
the integrated coil. Some aids combine these two
modes of operation with the MT posi- tion. It
allows the hearing impaired to perceive both
ambient noise and inductively transmitted
signals.
DCL20-65 | Manuel d’installation et d’utilisation | Installation and user manual |