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Sound is normally transmitted to a listener through the air by
vibrations, which are received by the ear. All the sound in an area will
be heard as the sum of signals whether they are the desired sound or not.
The hard of hearing can find it more difficult to separate the sounds they
want to hear from the background noise. A standard hearing aid will
amplify all sounds in an area, and although this can assist in hearing ,
it does not help in an environment where there is significant background
noise.
An audio induction loop systems compises
a large loop of wire run around the area conected to a special amplifier.
Hearing loops help the hearing aid user by providing a clearer link from
the sound source to the hearing aid. This is achieved by generating a
magnetic field at audio frequency in the area. The magnetic field is
generated by driving an audio frequency current through a loop of wire
that surrounds the area in question.
The loop driver will normally take its
signal input from a microphone system or from a Public Address system, .
It is therefore important to ensure that the signal input to the induction
loop system is what the hearing aid user will want or need to hear. To do
this, the design must correctly identify the sound sources that the
hearing aid user will benefit from hearing. It is not sufficient to simply
state that 'all sounds' in the room should be carried on the loop system.
In order to design loop system, the
original data upon which the system is designed, must be accurate and
complete. The complexity and amount of equipment required to drive the
loop system depends to a great extent on the size of area to be covered as
well as the building construction. Large amounts of metalwork contained
within the loop area, especially if such metalwork is formed into closed
electrical paths ie circles or other connected shapes, will tend to drain
energy out of the loop system. In such cases, specialist loop design and
more amplifiers will be required to overcome these losses.
A further complication is that the
losses due to metalwork are frequency related. the sound canbe muffled and
indistinct. Compensation can be applied to the loop systems to overcome
this effect by lifting the high frequencies.
Loop systems are governed by
internationally agreed standards that precisely define how strong the
magnetic field must be to allow a hearing aid user to hear well, clearly
and without distortion. Achieving this precise field strength across the
area of intended coverage is determined by the design .
Perimeter loops typically have a
magnetic field up to four times the width of the loop itself and hence
signals can be heard for considerable distances. If this causes problems
relating to confidentiality or adjacent room spill then special loop
design can reduce the spill distance . The
main types of loops are
1. Local Loops
2. Perimeter Loops
3. Cancellation Loops
4. Low Spill Phased Arrays
BLAKEGLOW select
.
BLAKEGLOW systems
can be invisible plastered into the wall, ceiling laid or burried under
floor
.
BLAKEGLOW provide
hearing loop systems for
schools sport’s centres, leisure centres, swimming pools, shops, offices
, call
centres and courts.
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