Say what? How hearing loops amplify one voice above the rest


A tiny coil in a hearing aid translates electromagnetic waves, allowing the wearer to listen to one source in a sea of background noise. Jake Port describes how it works in his latest tech explainer.


Hearing aids can amplify sounds well enough, but to discern one source above all others is easier with a hearing loop.
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If you find yourself trying to talk to someone in a loud, busy bar or at a party, you probably find it quite difficult to hear what they're saying. Background noise generated by other people in the room, music or other loud sounds muffle your and their words.

Now imagine this happened every time you went somewhere with moderate background noise, such as a theatre, train station or university – where not hearing an announcement could mean missing a performance, train or lecture.

This is one of the biggest issues faced by the hearing impaired who rely on a hearing aid.

While the device can amplify sound, it isn’t great at focusing on one voice among tens or hundreds. This is where the hearing loop comes in. But what is it and how does it work?

Essentially, the hearing loop lifts one voice to stand out of a crowd by combining an electromagnetic field with a special component of the hearing aid, known as the telecoil or T-coil.

This small metallic tube wrapped in copper wire acts as a tiny antenna. Its job is to take an electromagnetic field and convert those signals to audio.

When an alternating current is passed through a border of conductive metal along the outskirts of a space, such as a theatre or room, it generates an electromagnetic field.

When a person with a hearing aid steps into the room (and the field), the telecoil inside their device picks up that electromagnetic energy. The electromagnetic waves are converted back into electricity, which is then processed by a computer chip into audio.

The wearer of the aid controls this system. A hearing aid must be switched to the T mode to begin using the telecoil.

So what does this all mean?

Let’s move from the party to the classroom. Say you were trying to listen to a lecturer using a hearing aid. You notice the hearing loop sign and switch your aid to T-mode.

The lecturer begins speaking into a microphone hooked up to an amplifier. This amplifier connects not just to the speakers, but also to the hearing loop, transmitting an electromagnetic field.

The hearing aid converts the electromagnetic field into an electrical signal, and through a processor, back into the voice of the lecturer.

Suddenly the lecturer sounds loud and clear rather than muffled and washed out by other students’ conversations.

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