Health and Safety Information 134
M-Ratings
: Phones rated M3 or M4 meet FCC requirements and are likely to generate less interference to hearing
devices than phones that are not labeled. M4 is the better/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 is synonymous for T ratings. 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 is 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.
Other Medical Devices
If you use any other personal medical devices, consult the manufacturer of your device to determine if it is
adequately shielded from external RF energy. Your physician may be able to assist you in obtaining this
M3 + M2 = 5
T3 + T2 = 5
