Klarinet Archive - Posting 000681.txt from 2003/08

From: joseph.wakeling@-----.net
Subj: Re: [kl] closing the reed
Date: Tue, 26 Aug 2003 13:17:35 -0400

Tony Pay wrote:

<< We had a similar confusion of levels here when we talked about
'difference tones'. Some people thought that the variation in amplitude
associated with the sum of two sine waves was 'appreciated' by the eardrum.
And, I have to admit, I thought so too for many years.

But in fact, the eardrum is 'too busy' -- har har -- 'obeying' the forces
involved. >>

What a wonderful coincidence you should mention that. I am in Copenhagen at
the moment at a conference on complex systems science and have just attended a
wonderful talk on the very issue of how so-called "difference" tones are
perceived.

In fact "difference" tones is a serious misnomer. There is psychophysical
data from the 1960s that shows that, if you start with two tones of a given
frequency difference (and a resulting perceived pitch), and then raise the two
pitches while *keeping the frequency difference between them the same*, a
change in pitch is actually observed. But Helmholz' ideas have had so much
influence that this is still not widely appreciated.

Anyway, the talk I attended was by a friend of mine called Dante Chialvo who
trained as a medical doctor and has since had a wide and colourful research
career spanning a great variety of biological subjects. Preprints of his
papers explaining the "difference tone" phenomenon can be found here:

http://www.apkarianlab.nwu.edu/~dchialvo/psprints.html

The top two papers in the list are the ones in question.

-- Joe

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