The 2011 ANSI Standard that applies to all devices certified prior to December 5, 2023 includes two types of ratings: a microphone (M) rating and a telecoil (T) rating.
The ratings indicate how well devices reduce interference (buzzing, humming or whining noises) and increase signal quality to a hearing aid operating in microphone (acoustic) or telecoil (inductive coupling) mode. Your device and your hearing aid have their own M-rating and T-rating. You can use the ratings to predict the compatibility of a device and a hearing aid. The scale ranges from M1 to M4 for microphone mode and T1 to T4 for telecoil mode. Devices with higher rating numbers are less likely to interfere with hearing aids and are more likely to provide a better experience.
The M-rating is important for hearing aids that operate in microphone or acoustic mode and use a microphone to pick up sounds from the device’s speaker. It measures how well the device reduces interference with hearing aids. The FCC considers a device to be hearing aid-compatible if it is rated at least an M3. M4 is the best M-rating.
The T-rating applies to hearing aids that contain a telecoil and operate in inductive coupling mode. It measures how well the device works with a hearing aid’s telecoil, which removes extraneous noise that would otherwise be picked up by a microphone. The FCC considers a device to be hearing aid- compatible if it is rated at least a T3. T4 is the best T-rating.
For more information about FCC wireless hearing aid compatibility guidelines, visit FCC.gov.