FM Systems

FM systems is a generic name to many solutions for hearing impaired that rely on FM as the communication method (FM stands for Frequency Modulation, which is a common and relatively simple Radio Frequency protocol, exactly the same method they use on radio broadcast). It can be used either with or without hearing aids.

How it works

A typical FM system has two components: a transmitter and a receiver.

Transmitter

  1. The transmitter can have a microphone to receive the sounds, or it can have some input jack that connects it to the sound source. The later can be used, for instance, if you need to transmit sounds from a stereo system.
  2. Some of the transmitters can be placed on a desk while others are wearable.
  3. The transmitter sends the sounds to the receiver using FM radio signals.

Receiver

The receiver receives the FM signals sent by the transmitter.
  1. If you use FM system with a neck loop receiver and hearing aids, the receiver sends the sounds to your hearing aids using T-coil. Meaning, you switch your hearing aid to T-coil mode, and the neck loop sends the signals directly to the hearing aid.
  2. Another popular receiver is a small device, plugged as a whole directly into your hearing aid. This is relevant for most BTE devices since they usually have the port needed (named DAI, three holes on the bottom of the hearing aid).  It is sometimes called Audio shoe.
  3. In case you use it with no hearing aids, there are few options of getting the sounds from the receiver to your ears. The classic is using the headset the system comes with. You just put it in your ears and hear whatever the Transmitter hears. Additional option is to plug your own headset or earphones into the receiver.

FM Systems Usages

I like to divide the systems to personal and public.

Personal

To yours ears only, usually covers a small area. You can use it for watching TV, listen to a teacher in a class where only you need and more.

Public

In this case, there is one transmitter that broadcasts to a large audience. It can be used on theaters, lectures, and more.

The idea is that anyone with the right FM receiver can hear whatever the Transmitter sends over the air.

Examples

Just to give you a taste, here are several examples and links to demonstrate few different FM systems.

  • This page shows FM systems from different types. They show some non-FM accessories on the same page too.
  •  
    This is PHONAK web page that shows their FM transmitters.

  • And this the MLxi, a universal FM receiver by PHONAK, that you can plug into a BTE device, in case it got a DAI port.





Important note and a disclaimer

I write this for the sake of hearing aids users that find themselves confused by all the wireless terminology and misunderstandings. Therefore, I try to keep things as simple as possible and I simplify things to make them clearer. In addition, the discussion here is in the context of hearing aids and hearing aids’ users. I don’t try to cover the entire wireless world here, and therefore, all the data is observed from the angle of a hearing aid user and for his/her benefit.





Got a question?
Don't hesitate, ask!

We got a Q&A page, check it out here.