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From: mmt@dciem.UUCP (Martin Taylor)
Newsgroups: net.physics
Subject: Re: music harmony
Message-ID: <353@dciem.UUCP>
Date: Mon, 5-Sep-83 16:00:40 EDT
Article-I.D.: dciem.353
Posted: Mon Sep  5 16:00:40 1983
Date-Received: Mon, 5-Sep-83 16:32:55 EDT
References: <4796@sri-arpa.UUCP>
Organization: D.C.I.E.M, Toronto, Canada
Lines: 40

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The human ear determines pitch by having cilia in the colea of
the inner ear that resonate.  It is a pretty specatular realtime
Fourier transformer.  Since each cilium(?) only detects pitch and
not phase, the ear cannot detect phase differences.  The typical
vibrations and waves physics experiment is to have two tone
generators whose phase difference can be adjusted.  The ear
cannot tell the difference.
==================

This statement is a load of hogwash. It is a physicist's idea of how the
auditory system works.

Errors: (i) Phase information is available in the different neural frequency
channels up to around 4 kHz, and is routinely used in binaural detection
of direction up to about 1500Hz.
(ii) Pitch and frequency are completely different concepts. The individual
nerve fibres have maximally sensitive frequencies, and if the ear is
reasonably normal, a sine wave of a given frequency will sound as if it
has a unique corresponding pitch. However, it is possible to set up
conditions using high harmonics of a low fundamental frequency, so that
the pitch heard is that of the non-existent fundamental. Furthermore,
if the frequencies of all these "harmonics" are shifted up or down
by a certain amount, the perceived pitch will shift by a smaller amount.
(iii) Under laboratory conditions, it is possible to demonstrate
perceptual effects that DO depend on the relative phases of fundamental
and harmonics.
(iv) The auditory system is very complex, and by no shred of the
imagination could it be considered as a Fourier transformer.
To say so is like equating the visual system to a camera!


If you are interested, look through a few back issues of the Journal
of the Acoustical Society of America. There is a good index in every
June and December issue.

Martin Taylor

PS. Psychoacousticians please don't flame at the oversimplifications
above -- I'm trying to make it brief.