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Loudness decay (fwd) (fwd)

Jeffrey G. Sirianni sirianni at UTS.CC.UTEXAS.EDU
Fri Dec 15 12:00:22 EST 1995

>In article <199512080614.AAA03993 at curly.cc.utexas.edu>,
>Jeffrey G. Sirianni <sirianni at UTS.CC.UTEXAS.EDU> wrote:
>>Greater decay in the high frequencies indicates a cochlear lesion and
>>not a retrocochlear lesion
>The decay also happened in a promontory stimulation test which was part
>of an evaluation to see if a cochlear implant would be indicated.
>Therefore, the cochlea itself is not the cause of the strange
>symptoms.  It's either the auditory nerve or the brain.

I do not know enough about promontory stimulation to comment on this.  If
others out there know more, please comment...

>I wonder if it could somehow be caused by adapting to tinnitus.  Since
>tinnitus tends to sound like a steady tone or other steady sound, could
>it be that the auditory nerve and/or auditory processing in the brain
>has learned to filter out all steady tones and other steady sounds that
>last more than a couple of minutes?  The fact that the sound comes back
>to full loudness instantly if it's interrupted for even a fraction of a
>second seems to support this.

I'm still pondering this one... I still consider it tone decay and am not
sure whether tinnitus adaptation is related...

>An MRI is now scheduled, as you suggested.  But so is a cochlear
>implant, a few weeks later, if the MRI doesn't show anything.  With the
>cochlear implant, it might be easier to analyze the strange symptoms,
>assuming they continue then.  In particular, it will be easy to say for
>sure that none of them are caused by hair cells.  But in any case,
>since the problem only happens with steady tones, and not when the tone
>is interrupted, nor with any kind of modulated sound, it's really just
>of academic interest, because in real life there are very few
>situations where anyone wants to listen to a steady tone for more than
>a minute.

Would someone please comment on the contraindications of a coclear implant
in terms of findings from promontory stimulation testing.

>I'm not sure if I mentioned this, but an OAE and brainstem test (BSER)
>showed no response at all.  The BSER used clicks which tested from
>2000-8000 Hz.  I probably didn't mention these tests because they were
>only done recently, and my last posting on this subject was probably
>before that.

Your findings seem to make sense considering the amount of hearing loss that
is present.  Have you performed any MLR testing in frequency regions with
minimum hearing loss, or is the loss pretty extensive throughout the entire
frequency range?

This continues to be interesting discussion material...


* Jeff Sirianni                        *
* University of Texas at Austin        *
* Communication Sciences and Disorders *
*                                      *
* sirianni at uts.cc.utexas.edu           *
* jgsaudio at aol.com                     *

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