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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. To ensure
that the Hearing Aid Compatibility rating for your phone is maintained, secondary transmitters such as
Bluetooth® and WLAN components must be disabled during a call.
For information about hearing aids and digital wireless phones
Wireless Phones and Hearing Aid Accessibility
http://www.accesswireless.org/
Gallaudet University, RERC
http://tap.gallaudet.edu/Voice/
The Hearing Aid Compatibility FCC Order
http://hraunfoss.fcc.gov/edocs_public/attachmatch/FCC-03-168A1.pdf
Hearing Loss Association of America [HLAA]
http://hearingloss.org/content/telephones-and-mobiledevices
Caution: Avoid potential hearing loss.
Prolonged exposure to loud sounds (including music) is the most common cause of preventable hearing
loss. Some scientific research suggests that using portable audio devices, such as portable music players
and cellular telephones, at high volume settings for long durations may lead to permanent noiseinduced
hearing loss. This includes the use of headphones (including headsets, earbuds and Bluetooth or other
wireless devices).
Exposure to very loud sound has also been associated in some studies with tinnitus (a ringing in the ear),
hypersensitivity to sound and distorted hearing. Individual susceptibility to noise-induced hearing loss and
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