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Mobile phone
Some hearing aid users have reported a buzzing
sound in their hearing aid when they are using
mobile phones, indicating that the mobile phone
and hearing aid may not be compatible.
The ANSI C63.19 standard determines the
prediction of compatibility between a specific
hearing aid and a mobile phone by adding the
numerical value of the rating for the hearing aid
immunity to the numerical value of the rating for
the mobile phone emissions.
A sum of 4 would indicate that the combination
of wireless device and hearing aid is usable; a
combined rating that equals 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 different 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.
