A T-Loop1 is an audio transmission system used to help mild to severely2 deaf people hear specific communications such as a telephone call or a conversation with the bank cashier. Unlike fully hearing individuals, those with hearing difficulties are unable to 'screen out' background noise and have to concentrate that much harder to reach through to the noises they need to hear. By switching their hearing aids to the 'T' position3, deaf people are able to pick up only those signals transmitted by the T-Loop. There are two main types of T-Loop: personal and external.
The Personal Loop
Personal loops are worn over the head or behind the ear, and are used to listen to personal music players, radios and computers – basically anything that you could normally use a standard pair of headphones to listen to. Headphones do not work well with hearing aids – the big earmuff ones are at best uncomfortable, while the tiny teardrop ones are nigh on impossible to fit.
Available for one or both hearing aids, the T-Link takes the form of a hook placed behind the ear beside the hearing aid. This can mean the back of the ear can become uncomfortably crowded, particularly if the deaf person is wearing a pair of glasses as well. They are, however, the least conspicuous option.
The Inductive Loop
This is simply a loop of insulated wire placed over the head, from which the hearing aids can pick up their signal. Usually designed with little regard for style, it can look slightly odd unless hidden beneath a hat or a scarf of some sort.
The External Loop
These are stationary, previously-existing T-Loops that can be tuned in to by hearing aid users. Instead of going around the neck or beside the hearing aid, the loop goes under the carpet or across the wall of the building the hearing aid user happens to be in.
There are a variety of T-Loop boxes on sale that can be plugged into a television, computer or radio. They usually come with their own tone and volume controls. It is possible to How to build your own T-Loopbuild your own T-Loop in your home or place of work and some equipment such as telephones will come with built-in T-Loops.
The T-Loop sign is a square sticker featuring a stylised white ear with a diagonal line drawn across it, and it tells you that a T-Loop is present in the building you are about to enter. T-Loops can be found in a variety of places; usually in public service buildings such as stations, phone boxes, banks, hospitals and post offices.
How Does it Work?
When the hearing aid is switched to the 'T' position, the microphone is (usually) turned off and a small pickup coil turned on. This coil is able to pick up changes in magnetic signals within the loop wire and to convert these signals into sound. The induction loop is fed from a loop amplifier or a headphone socket.
Advantages and Disadvantages.
For those who are hard of hearing, background noise is very intrusive. T-Loops are designed to eliminate distracting chatter, humming machinery or clacking footsteps and give the user a direct link into whatever it is they want to listen to. It also reduces the problem of feedback at high volumes, meaning that the T-Loop can be turned up much louder than a normal hearing aid. Any T-Loop can be listened to by any hearing aid user – all you need is a 'T' switch on your hearing aid.
Unfortunately, this does mean that all background noise is cut out, including useful things such as people talking to you, front door bells and fire alarms. There is an option to have a 'transparent' T-Loop in the latest hearing aids, but it does mean you will still be listening to background noise that is often intrusive and distracting.
The T-Loop is neither the best understood nor best looked-after system, and often T-Loop reception is appalling. This may be because it has such a small 'audience'. It cannot be listened to without a hearing aid. Interference is possible from nearby T-Loops and other electronic devices, leaving you to 'watch' one film at the cinema while 'hearing' the one showing on the screen next door, for example. Also, T-Loops have a very short range before they become inaudible.
1 A tele-coil transmission loop, also known as an induction loop.
2 The rating goes from mild, moderate, severe to profound for each ear. Bilaterally (both ears) profoundly deaf people are unlikely to have any hearing at all.
3 Usually located between the 'on' and 'off' positions.