Biomedical Engineering Reference
In-Depth Information
of mobile phone RF interference ratings
and hearing aid RF immunity ratings,
often found on the packaging of mobile
phones. Both sources of information are
necessary to maximize hearing aid com-
patibility. Some of this information may
be found publicly in an Internet search,
and other pieces may require assistance
from a phone provider and/or hearing
professional. The FCC requires that hear-
ing aid compatible mobile phone provid-
ers indicate a quality measure (or rating)
of how much RF emission (interference)
is produced by the mobile phone.
M-ratings will be important for indi-
viduals who plan to use the acoustic cou-
pling method using the microphone of
the hearing aids. The ratings will be listed
as M1, M2, M3, or M4 with M1 having
the greatest interference (least compat-
ible) and M4 having the least interference
(most compatible). Aiming for mobile
phone M-ratings of M3 or M4 is a good
strategy.
T-ratings will be important for indi-
viduals who plan to use the inductive
coupling method with hearing aids that
have a built-in telecoil. Some telecoils
need to be programmed or activated by
the audiologist, if the telecoil option is
available. Similar to M-ratings, the tele-
coil ratings will be listed as T1, T2, T3,
or T4 with T1 having the greatest inter-
ference (least compatible) and T4 having
the least interference (most compatible).
Aiming for mobile phone T-ratings of T3
or T4 is a good strategy. Table 10-1 lists
three tips that may be helpful to maxi-
mize the use of the telecoil. It should be
noted that some mobile phones only have
Table 10-1.
telecoil tips for Mobile Phone Use
Telecoil
Tip
Description
tip 1
telecoils are aligned in hearing aids with a particular arrangement (vertical),
and it may be in a slightly different location in different hearing aid models. after
activating the telecoil in your hearing aid, it may be helpful to take the mobile
phone and hover around the hearing aid to find what many refer to as the “sweet
spot.” It may also help to rotate the mobile phone slightly forward or backward to
improve the volume or gain.
tip 2
If two hearing aids are worn, it may help to activate the telecoil only in the better,
or preferred ear, while turning the other hearing aid completely off. this has the
effect of cutting out background noise and stray rF emission on one side of the
head so that one can focus completely on the conversation. For safety reasons, it
may help to keep the other hearing aid for environmental awareness.
tip 3
Some individuals may benefit from (or prefer) listening to their mobile phone
through both hearing aid telecoils at the same time. this is possible with the use
of wearable induction earhooks/silhouettes or an induction loop. One may be able
to plug this wearable induction accessory directly into the audio jack of the mobile
phone. an audiologist or assistive listening device supplier may be able to assist
with this option.
