User's Guide

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box or a label located on the box.
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 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.