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Appendix | 139
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 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.
For information about hearing aids and digital wireless phones
FCC Hearing Aid Compatibility and Volume Control:
http://www.fcc.gov/cgb/dro/hearing.html
Gallaudet University, RERC:
http://tap.gallaudet.edu/DigWireless.KS/DigWireless.htm
Self Help for Hard of Hearing People Inc. [SHHH]
www.hearingloss.org/hat/TipsWirelessPhones.htm
The Hearing Aid Compatibility FCC Order:
http://hraunfoss.fcc.org/edocs_public/attachmatch/FCC-03-168A1.pdf