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Cell phone
Some hearing aid users have reported a
buzzing sound in their hearing aid when
they are using cell phones, indicating that
the cell phone and hearing aid may not be
compatible.
The ANSI C63.19 standard determines
the prediction of compatibility between
a specic hearing aid and a cell phone
by: adding the numerical value of the
rating for the hearing aid immunity to
the numerical value of the rating for
the cell phone emissions. A sum of 4
would indicate that the combination of
wireless device and hearing aid is usable;
a combined rating that equals at least 5
would provide normal use; a combined
rating of 6 or greater would indicate
excellent performance.
Whereas all hearing aids have acoustic
coupling, only the larger hearing aids
have the physical space for telecoil
(inductive) coupling. These two types
of coupling have dierent rating scales
(M1-M4 for acoustic coupling and T1-T4
for telecoil coupling, respectively) and
both ratings are therefore relevant when
predicting the compatibility of a particular
hearing aid.
For a hearing aid with both acoustic
coupling and telecoil coupling with a
rating of M4/T2 and with a telephone
rating of M3/T3), the combined rating
is 7 (M4 + M3) for the acoustic coupling
and 5 (T2 + T3) for the telecoil coupling.
According to the guidelines given above,
both types of coupling will thereby be
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