Locations of use

Induction loops are a requirement under legislation for most service providers and public buildings in locations where the public has a need to communicate with staff or listen clearly to announcements, speeches or other similar audible content. Typical sites with a requirement include theatres, cinemas, places of worship, conference halls, banks, supermarkets, airports, shopping centres and bus and train stations.

It is vital that the actual practical use of a proposed induction loop is considered in full before embarking on an installation, this is particularly important on a new build construction project or scheme where an effective and practical system is often difficult to achieve in some locations, particularly as the application has not been considered carefully.

See examples of practical audio frequency induction loop systems and some of the potential problems here.

Loop Coverage

The most important part of setting up an induction loop is the strength of the magnetic field. Fortunately international agreement has been reached on the most appropriate field strength for hearing aid purposes and this specification is the subject of an international standard IEC118-4 (British Standard BSEN60118 pt.4): Magnetic field strength in audio induction loops for hearing aid purposes.

The standardised value of field strength should ensure that when a person listening through a hearing aid switches from ‘T’ to ‘M’ the sound of someone speaking normally should be about as loud as the signal from the loop. Any gross departure from the recommendation could result in an unsatisfactory system.

Setting up and measuring the levels are vital for a compliant system. all induction loop systems supplied and installed by PAS are setup in accordance with BSEN60118-4 and certified upon commissioning. Beware many low voltage contractors may offer induction loop systems but are unable to test or certify their installations.

Low Overspill Loops

Induction loops create a magnetic field that is fairly consistent within the loop and reduces outside of the loop. Outside of a simple rectangular loop there is still an audible signal as far as 4 times the width of the room away from the loop.

There are many situations where the loop coverage needs to be contained within a specific area, either for security (such as council chambers or courts) or where many rooms exist side by side (such as schools and colleges).

So in order to reduce the spillage from a loop, the solution is usually to use a low spill array arrangement. These loop solutions are a little more complex, but are used widely in theatres, educational establishments, cinemas and conference centres.