FM system
A wireless assistive listening device that transmits a speaker's voice via frequency-modulated radio signals directly to a receiver worn by or coupled to the listener, improving the signal-to-noise ratio at the listener's ear.
Full Definition
An FM (frequency modulation) system consists of a transmitter worn by or near the speaker and a receiver coupled to the listener's hearing aid, cochlear implant, or worn as a standalone device. By transmitting the speech signal directly to the listener, FM systems effectively negate the degrading effect of distance, reverberation, and background noise on speech intelligibility. They are widely used in educational settings for children with hearing loss and in rehabilitation programmes for adults. Editors should note that 'FM system' is the conventional styling; 'FM-system' with a hyphen is non-standard. In documents referencing newer technology, FM systems may be compared with or replaced by digital radio systems (DM systems).
Usage
Usage note: Do not hyphenate 'FM system'. Distinguish from DM (digital modulation) systems, which are increasingly preferred in educational contexts. Clarify coupling method (direct audio input, neckloop, or integrated receiver) when relevant.
In Context
- "The school's FM system delivered the teacher's voice at a consistent +15 dB SNR advantage over classroom noise." — Educational audiology report
- "The child's FM system receiver was coupled directly to her behind-the-ear hearing aid via a dedicated audio shoe." — Hearing technology fitting documentation