Telecoils in Plain Language

February 2005

Editor: I often refer to the people who read this newsletter as the "movers and shakers" in the hearing loss world, because you are! Because of your deep involvement in this community, you're probably so aware of the advantages of telecoils that you don't think much about them. Unfortunately, many audiologists and hearing aid dispensers continue to provide a lot of hearing aids without telecoils, with the result that many people who could benefit from them are simply unaware of their existence.

Here's a great primer on Telecoils from NVRC News. I encourage you to save it and distribute it to professionals and consumers who might benefit from it! Be sure to credit NVRC News when you do.

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A hearing aid option that is referred to as a telephone switch, telecoil, t-coil or t-switch can sometimes be confusing.

Below is a description of how a telecoil works and how it can benefit a person with hearing loss.

What is a Telecoil? A telecoil is a special circuit inside the hearing aid. It is a small coil of wire designed to pick up a magnetic signal. Telecoils can only fit in two styles of hearing aids: In-The-Ear and Behind-The-Ear aids. The smaller hearing aids are not large enough to fit the telecoil.

How does a Telecoil work? While the microphone on a hearing aid picks up all sounds, the telecoil will only pick up an electromagnetic signal. It turns off the hearing aid microphone, picks up the signal and the hearing aid converts it to sound. This magnetic signal (more technically known as an induction signal) is created from hearing aid compatible telephones and assistive listening systems.

Why is a Telecoil important for the telephone? Many people report feedback (or squealing) when they place the handset of the telephone next to their hearing aid. The telecoil can eliminate this feedback because the hearing aid microphone is turned off and the hearing aid only amplifies the signal coming through the telecoil. Telephone handsets emit the magnetic signal from the ear-piece. When placed correctly near the telecoil, the sound should be transmitted clearly. That is why some people must place the ear-piece slightly behind their ear rather than directly over the ear.

What else can a Telecoil be used with? Assistive listening systems (either FM systems, audio loops, etc) have a neckloop as a listening option. The neckloop transmits the induction signal for the hearing aid telecoil, so you can turn off all background noise while only hearing the sound going from the FM system's microphone to your FM receiver and neckloop. Audio loop systems also emit the electromagnetic signal so you only have to switch to telecoil to pick up sound.

Are there any problems with using a Telecoil? There are other sources of electro magnetic signals that can interfere with the performance of the hearing aid telecoil. Fluorescent lights, television screens, computer monitors and electrical panels can cause a 'humming' sound when you turn on your telecoil. The humming sound interferes with your ability to hear clearly. Sometimes you can move and the interference is lessened.

Sometimes it is not effective to have both hearing aid telecoils turned on (as when using am FM system) because you may not be able to hear your own voice. You'll only hear what the speaker is saying. If you need to hear classroom discussion, etc., you have two choices. One is to have an M/T switch on your hearing aid that allows the microphone to stay on at the same time the telecoil is operating. Another option is to turn only one aid on telecoil so that you can monitor other sounds in the room. A third option is to use an FM system with a built-in environmental microphone that will allow you to pick up sounds near you at the same time you are picking up the speaker's voice.

I've been told Telecoils aren't effective. Is that true? There are telecoils that are not strong. There are also people who don't notice a benefit when trying to use the phone because the phone does not emit a strong enough signal.

There are ways to overcome a weak signal or weak telecoil and allow your hearing aid to perform better. One way is to boost the signal strength by using an amplified telephone. Another way is to use the power of an assistive listening system.

If the volume on your hearing aid seems to drop when you turn on the telecoil, increase the volume on your hearing aid. This will help increase the signal strength. An amplified telephone also boosts the electromagnetic signal so that your telecoil can perform better.