Hearing Aid Compatibility (HAC) Ratings systemThe wireless telephone industry has developed ratings for some of their mobile phones, to assist hearing device users in finding phones that may be compatible with their hearing devices. Not all phones have been rated. Phones that are rated will display the following text and/or icons on the product packaging:
The ratings are not guarantees. Results will vary depending on the user's hearing device and hearing loss. If your hearing device happens to be vulnerable to interference, you may not be able to use a rated phone successfully. Trying out the phone with your hearing device is the best way to evaluate it for your personal needs.
M-Ratings: Phones rated M3 or M4 meet FCC requirements.
They are likely to generate less interference to hearing devices than unrated phones.
M4 is the better/higher of the two ratings(M3 & M4).
T-Ratings: Phones rated T3 or T4 meet FCC requirements.
They are likely to be more usable with hearing device's telecoil than unrated phones.
T4 is the better/higher of the two ratings(T3 & T4) *Note that not all hearing devices have telecoil in them.
In addition to rating wireless phones, the ANSI standard also provides a methodology for rating hearing aids from M1 to M4, with M1 being the least immune to RF interference and M4 the most immune. To determine whether a particular digital wireless telephone is likely to interfere with a particular hearing aid, the immunity rating of the hearing aid is added to the rating of the telephone. A sum of four indicates that the telephone is probably usable; a sum of five indicates that the telephone would probably provide normal use; and a sum of six or greater indicates that the telephone would probably provide excellent performance with that hearing aid. Note that not all hearing aids are rated.