Zwicker effect

Didier A. Depireux didier at tango.isr.umd.edu
Tue Jun 3 22:24:14 EST 2003


r norman <rsnorman_ at _comcast.net> wrote:

> A lot of the tinnitus speculation assumes it is a peripheral
> phenomenon.  That is, there really is a sound to be heard or else that
> the hair cells (or auditory nerve neurons) are generating it.  What if
> it were a central process?  I was told that my situation was most
> likely caused by the ABSENCE of auditory nerve activity -- the central
> auditory centers "didn't like" the absence of normal stimulation and
> took things into their own hands.  That is, the frequency range of the
> ringing was higher than my upper limit of hearing.  Over the years as
> the my high frequency cutoff dropped lower and lower, so did the
> tinnitus tone. 

There are 2 types of tinnitus, to zeroth order approximation, objective and
subjective. 
Objective tinnitus is the one that your audiologist can record himself. 
Actually, a healthy ear rings once in a while, that is when you were young,
you heard about once a week or so a very high pitch sound, lasting about 30
seconds, that sounded like one of these old TVs warming up. It is likely due
to hair cells inside your cochlea going into spontaneous oscillations. The
hair cells cause vibrations to propagate in the fluids inside your cochlea,
so you hear the sound, but also someone who puts a microphone in your ear
canal will be able to record what you hear! As a matter of fact, a healthy
ear is continuously generating these sounds (look up "spontaneous
otoacoustic emissions"), but they are 6-15 dB below your threshold of
hearing. You only hear the very loud ones. 
Subjective tinnitus is poorly named, but is basically any tinnitus that is
not objective. It is the kind of tinnitus all of us can experience if we
take 3 gms of aspirin, for instance. It can also occur in strange cases, the
most unpleasant being related to your story, namely a patient will have her
8th nerve resected for vertigo, which will make her deaf in that ear, and
following surgery, she hears a very loud, typically high pitch sound. So the
poor patient is now deaf but hears a continuous tone. The causes of
subjective tinnitus are numerous and poorly understood, to put it mildly.
A common treatment for tinnitus, as a first line, is xanax or clonazepam.
However, you should do your homework and search for yourself. For instance,
many a person has had good success by reducing caffeine and especially
reducing salt (sodium) intake. 
http://www.tinnitus.org/
http://www.tinnitusanswerboard.com/
would be a start. 

						Didier

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