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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 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.
M3 + M2 = 5
T3 + T2 = 5
T919 Roxy.book Page 169 Thursday, September 25, 2008 5:01 PM