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higher of the two ratings.
T-Ratings: Phones rated T3 or T4 meet FCC requirements and are likely to generate
less interference to hearing devices than phones that are not labeled. T4 is the better/
higher of the two ratings.
Hearing devices may also be rated. Your hearing device manufacturer or hearing health
professional may help you find this rating. Higher ratings mean that the hearing device
is relatively immune to interference noise. The hearing aid and wireless phone rating
values are then added together. A sum of 5 is considered acceptable for normal use.
A sum of 6 is considered for best use.
In the above example, if a hearing aid meets the M2 level rating and the wireless phone
meets the M3 level rating, the sum of the two values equal M5. This should provide the
hearing aid user with “normal usage” while using their hearing aid with the particular
wireless phone. “Normal usage” in this context is defined as a signal quality that’s
acceptable for normal operation.
The M mark is intended to be synonymous with the U mark. The T mark is intended to
be synonymous with the UT mark.
The M and T marks are recommended by the Alliance for Telecommunications
Industries Solutions (ATIS). The U and UT marks are referenced in Section 20.19 of the
FCC Rules.
The HAC rating and measurement procedure are described in the American National
Standards Institute (ANSI) C63.19 standard.
To enter that the Hearing Aid Compatibility rating for your phone is maintained,
secondary transmitters such as Bluetooth and WLAN components must be disabled
during a call.