What is an FM System?

An FM system is an assistive listening device (ALD) that uses FM radio waves to transmit localized speech to a localized listener, in a comparable way to how a radio station uses waves to transmit audio from a speaker into someone’s radio.

The process involves two key pieces of technology alongside FM radio waves: a specialized microphone worn by the speaker and a device attached to the listener’s hearing aid, called a boot. As the speaker is talking, the microphone picks up their words and transmits them directly to all boots programmed to the FM frequency of the speaker.

The first personal FM product was released in 1968 by Phonic Ear. It was revolutionary at the time because it was fully wireless, enabling people to move around a physical space (like a lecture hall) and still hear the speaker clearly. The first iteration FM system was quite large and had multiple pieces, which proved cumbersome for users. While iterative improvements came over the years, another company – Phonak – released the first miniature version FM system in 1996, which made it pocket-sized and much more comfortable for users.

Continued improvements happened in the early part of the 21st century and by 2013 Phonak had another version out that had both a further-reduced size and a feature that helped significantly with background noise reduction. Another part of this new improvement is the movement from FM radio waves to using a digital modulation (DM) technology, which aids in background noise reduction. While widely seen as an improvement, some disability scholars believe the DM system functionality will cause the end of the FM system as the standard for assistive listening.