wierd problems with KAMP

Tapeworm tapeworm at net2.intserv.com
Wed Jan 15 22:25:19 EST 1997

Susan Moore <smoore at otolaryngology-po.oto.uiowa.edu> wrote in article 
> and one patient had a VERY wierd sound when opening and shutting the
battery door
> of a CIC that sounded like an airplane taking off and landing that was 
> intermittent.  Furthermore, the aid frequently wouldn't work right away
after the 
> airplane sound/closing batt. door and took several seconds to come on.

Hard to say, but it sounds like normal K-Amp function.  The K-Amps I have
used have a "warm-up period" of 3-6 seconds.  The reason you're
experiencing the weird sound on the CIC may be that since there is no
volume control, you're hearing the behavior of the circuit at a volume-on
setting, instead of a "gradual-on" effect that you'd get with an ITE in
which you'd turn on at minimum volume and then increase the volume setting.
 The intermittency of the effect may be associated with this:  I've noticed
that while K-Amps do need to "warm-up" they also seem to hold the charge
even after it has been turned off, and it takes a bit of time for it to
dissipate.  So if you notice the effect, turn the aid off, and immediately
turn it back on again, the effect is not repeated; but if you let it sit
for a while, it will repeat.

> The other 2 KAmp problems have been similar.  The patient reports
popping, ringing, 
> and intermittentcies in the aid that they do not think is their hearing
and that 
> battery changes do not fix.  They say it is a different sound than the
> that the aid does when the battery is on its last legs. 

Again, it could simply be the normal functioning of the K-Amp.  The effect
that the patient reports could be the compression engaging and releasing,
which seems like the aid is malfunctining to someone who's previously worn
linear aids.  K-Amp's feedback also is often a "chirp" rather than a
continuous squeal.  The feedback loop begins, which causes the compression
to engage.  While the aid is in compression the feedback stops, and the
compression is released, which causes feedback again.  This happens up to
several times per second.

Or I could be completely wrong.

David Weesner,MA, CCC/A
New Jersey

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