Klarinet Archive - Posting 000026.txt from 2002/10

From: w9wright@-----.net (William Wright)
Subj: Re: [kl] Pitch difference between ears
Date: Tue, 1 Oct 2002 14:08:33 -0400

As fortune would have it (or perhaps unconscious impulse), I passed by a
medical library this morning. So I went inside and looked up
diplacusis.

Diplacusis can happen in a single ear. That is, the same ear hears two
pitches.

Various ear membranes and bones connect eventually to tiny hairs which
brush against nerve cells that form the organ of Corti (part of the
cochlea). These hairs cause the organ of Corti's cells to bend, and
this flexure causes the nerve cell walls to become porous to ions and
thus to begin a depolarization --- which is the beginning of a nerve
impulse that eventually is interpreted as sound.

If the hairs are damaged, or if something damages the Corti cells, the
resultant misinformation can be perceived as multiple pitches when, in
fact, only one 'fundamental' pitch exists.

The book listed several causes for damage to either the hairs or the
cells that begin the depolarization, but (according to the textbook)
damage to the hairs from loud noise is far and away the most common
cause. Although the textbook did not give numbers, the implication was
that 90%-95% of the cases are related to hair damage rather than to the
nerve cell damage.

Cheers,
Bill

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