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Re: Beats

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Dear List,

James Wright wrote:

> I'm working at home this morning and happened to hear a CBC interview with
> Glenn Gould's piano tuner (now retired).
> He made a very interesting comment regarding an affliction he developed.  He
> said that later in his life he developed a fairly persistent and
> intense tinnitus.  I was especially interested in the following anecdote:
> "It really drove me crazy.  For example, one day I was on a bus and at
> every stop, when the driver applied the brakes, they let out a steady
> high-pitched squeal.  Every time it happened, I could hear, very clearly,
> the beating between the squeal of the brakes and my tinnitus."

In reply to this Al Bregman wrote:

> It is possible that the piano tuner suffered from an otoacoustic emission;
> that is, an actual acoustic signal generated in the inner ear.

I agree completely. The beating between the "tinnitus" and the break-squeal of
the bus requires that mixing between the two sounds take place in a domain wher
the principle of superposition applies.

I have actually tried to obtain this kind of interference in a couple of
subjects suffering from "real" tinnitus, that is, a tinnitus that could not be
objectively measured as an otoacoustic emmision. None of these subjects reporte
any sort of interaction between the external tone and their tinnitus, although
they were able to freely adjust both level and frequency of the external tone.
My conclusion was that these subjects' sort of tinnnitus was genereated in such

a way that linear interaction between an external sound and the tinnitus "sound
was impossible.


Soren Laugesen
Oticon A/S
Research Centre, Eriksholm
Kongevejen 243
DK-3070 Snekkersten

Phone +45 49 22 00 01 ext. 13; Fax +45 49 22 36 29;
email slu@eriksholm.oticon.oticon.oticon.dk400.dk