Summary
The US rule for licence-free auditory assistance transmitters in the 72-76 MHz band, the older of the two US bands used by venue FM systems.
Key findings
- Restricts transmitters in these bands to use as auditory assistance devices.
- Confines emissions to a band 200 kHz wide centred on the operating frequency, lying wholly inside 72.0-73.0, 74.6-74.8 or 75.2-76.0 MHz.
- Limits field strength inside that 200 kHz band to 80 millivolts per metre at 3 metres, measured with an average detector; emissions outside it must meet Part 15's general radiated limits (15.209).
- Part 15's definition of an auditory assistance device (15.3(a)) includes assistive listening, audio description for the blind and simultaneous language translation, for people with disabilities, people who need translation, and others who benefit in places of public gathering such as churches, theatres and auditoriums.
Limits
A legal limit on the transmitter only: it sets no audio quality, range or receiver requirement. Because the definition includes language translation, interpretation systems use the same channels, and Part 15's general conditions (15.5) require these devices to cause no harmful interference and to accept interference from others. Date is the Federal Register publication of the section's latest amendment (78 FR 34927), as given in the eCFR source note; the text read was current to 6 October 2026.
Read the original
www.ecfr.gov/current/title-47/section-15.237
Cited in
- Auracast, hearing loop, infrared, RF or Wi-Fi: which suits which room?Disputed
- Which radio bands can venue FM and RF systems use, and what limits them?Partly answered
Cite this source
US Federal Communications Commission. 47 CFR 15.237: operation in the bands 72.0-73.0 MHz, 74.6-74.8 MHz and 75.2-76.0 MHz. Electronic Code of Federal Regulations (eCFR). 11 June 2013. https://www.ecfr.gov/current/title-47/section-15.237 (accessed 9 October 2026).
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