HAC - Hearing Aid Compatibility

Hearing Aid Compatibility (HAC) testing involves measuring the magnetic and electric field producted by a phone to ensure it does not interfere with the sound quality of a hearing aid. HAC testing was originally introduced in late 1970’s with the purpose of making it possible to couple a wired telephone with a hearing aid. Nowadays, these requirements have been extended to wireless devices.

FCC

Since 2005 the Federal Communication Commission (FCC) require that cellular telephone providers and manufacturers offer a growing number of handsets on the US market, which are compatible with hearing aids according to the standard ANSI C63.19. This standard specifies the audio magnetic field for T-coil coupling as well as the allowable RF interference level for E-field and H-field as a function of hearing aid RF susceptibility.

M & T Ratings

The wireless telephone industry has developed so-called M and T ratings to assist hearing aid users in finding wireless devices that may be compatible with their hearing aids. Wireless devices that are rated will have the rating displayed on their box together with other relevant approval markings.

• M-Rating
  Wireless devices rated M3 or M4 meet FCC requirements. M4 is the better/higher of the two ratings.
• T-Rating
  Wireless devices rated T3 or T4 meet FCC requirements and are likely to be more usable with a hearing device's telecoil ("T Switch" or "Telephone Switch") than unrated wireless devices. T4 is the better/higher of the two ratings. (Note that not all hearing devices have telecoils in them).

The availability of hearing aid compatible handsets is observed by the FCC. The target is a market coverage of at least 50% M-rated handsets and 2 handsets with T-rating per provider.

HAC measurements

CETECOM uses the HAC extension of the DASY4 test system to offer the following HAC measurement services:

• RF interference measurements according to ANSI C63.19, E-field emission and H-field emission.
• Audio frequency measurements according to ANSI C63.19, T-Coil signal amplitude, T-Coil frequency response and T-Coil signal to noise measurement.