
Induction
Loop System for the Hard of Hearing
Audio Frequency
Induction Loop Systems (AFILS) are installed in places where hearing
aid users will benefit from direct sound input to their personal hearing
aid. The user switches their hearing aid to the "T"-position
(Telecoil) - this reduces background noise and increases clarity of
speech information and the enjoyment of live sound. The direct sound
may come from dedicated microphones and/or the microphones used for
a sound reinforcement (loudspeaker) system.
Microphones for Audio Loop Systems
Hearing
aids have microphone(s) built-in to them. The loop induction system
is simply
a way of transmitting sound directly to the hearing aid. This is only
of benefit to a hearing aid user, when the microphone(s) connected
to
the loop system are better placed to to the source and therefore pick
up less unwanted (ambient) sound than the microphone(s) built into
the hearing aid. Ideally, microphones
should
normally
be less than
1 metre from the talker in quiet locations, and as close as 300mm in
some noisier environments. In theatre (stage) applications, this
can
be up to several metres, but only when the actors project their
voices and the background noise level is low. If more
than three
microphones are used for speech, then an automatic
microphone mixer is desirable, as recommended in the British Standard for best practice.
Examples
where a loop system is used
1. A
bank counter. The speech from the bank counter clerk
comes through a 'window', but the hearing aid microphone is
in the open plan area,
where there is other noise. A microphone near the bank clerk is much
better located to pick up 'wanted' sound, and with less general
noise
from the bank area. This also avoids the clerk having to raise their
voice, which would otherwise mean other people may
hear the conversation. (see also, Speech
Privacy Systems).
2. A
church. The hearing aid user could be anywhere in the
congregation, but a microphone(s) at the pulpit, lectern, or
a tie-clip mic on the
minister, is much better placed than the internal mic which is on
the hearing aid where the user is sitting. More 'wanted
sound',
less 'unwanted'
sound
from
background
noises in the church, and less reverberant sound.
A
hearing aid loop fed by a microphone that is much better
placed than the
hearing aid’s internal microphone, will be of significant benefit
to the hearing aider user.
Value
Added Tax (VAT)
Supply
may be zero rated VAT when purchased by registered disabled persons,
or for the benefit of hearing aid users by a registered charity or
equivalent church organisation. Ask
us for details.
If
you need ...
Equipment
We
supply loop amplifiers from several manufacturers, including Ampetronic,
AVX and UNIVOX and select the most appropriate unit for your application and budget.
You
can also buy DIY & portable loop systems at our Online
Audio Shop.