LG VX8600 User Manual page 114

Safety
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
112
VX8600
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
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
HLAA (Hearing Loss Association of America)
http://www.hearingloss.org/learn/cellphonetech.asp
The Hearing Aid Compatibility FCC Order
http://hraunfoss.fcc.gov/edocs_public/attachmatch/FCC-
03-168A1.pdf