Mobile Phone - Philips HearLink Series User Manual

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 instruments 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
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