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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.
When you're talking over the cell
phone, it's recommended you'd
turn the BT (Bluetooth) mode off
for HAC.
For information about hearing
aids and digital wireless phones
Wireless Phones and Hearing Aid
Accessibility
http://www.accesswireless.org/
hearingaid/
FCC Hearing Aid Compatibility
and Volume Control
http://www.fcc.gov/cgb/
consumerfacts/hac_wireles s.html