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Re: Beats

Al, et al.

It is a reminder of the phenomena described by Dix Ward 40 years or so
ago, in which you introduce a tone into the ear of a subject and they
report hearing that tone, plus 2F1-F2, where F1 is a (hypothetical)
locally generated tone in the ear, and F2 is the tone you are introducing.
We were reminded of those observations at the memorial session for Dix,
and the Penn State meeting of the ASA...for those who missed it.

Bill Kelly and I discovered a case of this at CID, in about 1975.  We
were asking an experienced listener to make an alternating binaaural
pitch match, using the method of adjustment.  When we lowered the
level of the tones (fixed frequency introduced into one ear and
variable in the other) to 10-15 dB SL, and asked her to "match the pitch
in your left ear with that in your right"  she responded, "should I match
the high one or the low one?"  We said, "baloney," or words to that
effect, and then, "sure, match the low one."  She matched the "high"
and the "low" tones with essentially equal accuracy, and they turned
out (as with Dix's subjects) to be the stimulus frequency and the cubic
difference tone.  We spent a bit of time trying to mask the internally
generated tone (which had a freq of about 1200 Hz) which she never could
hear, and which frequency never showed up in her matches.  Of course we
later learned about SOAE's and became convinced they were the source of
what we had been studying.  But by that time we had lost touch with that
S (who was both a musician and a very experienced lab subject), but there
must be lots more out there who can do that task.

Chuck Watson

On Mon, 30 Jun 1997, Al Bregman wrote:

> Jim,
> It is possible that the piano tuner suffered from an otoacoustic emission;
> that is, an actual acoustic signal generated in the inner ear.  I will
> forward your observation to the auditory list to see whether anyone else
> has a reply to your question.
> - Al
> ----------------------------------------------------------------------
> Albert S. Bregman,  Professor,  Dept of Psychology,  McGill University
> 1205  Docteur Penfield Avenue,   Montreal,  Quebec,  Canada   H3A 1B1.
> Phone: +1 514-398-6103  Fax: -4896 Email: bregman@hebb.psych.mcgill.ca
> Lab Web Page: http://www.psych.mcgill.ca/labs/auditory/laboratory.html
> ----------------------------------------------------------------------
> On Mon, 23 Jun 1997, James Wright wrote:
> > Hi Al,
> >
> > 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."
> >
> > It seems to me that this is a fascinating and rare/coincidental piece of
> > testimony for several reasons:
> >
> > 1) you have someone who happened to suffer from tinnitus
> > 2) who was also perceptive enough (as a result of training
> > and experience as a piano tuner) to describe the "beating" between the
> > tinnitus and an external sound.
> > 3) who happened to be on a bus with brakes producing a steady squeal
> > 4) the frequency of which happened to be within beating range of his
> >
> > With your understanding auditory physiology, do you think this anecdote
> > might tell us something we don't already know about beats, tinnitus, or
> >
> > Best - Jim
> >
> > James Wright
> > jawright@ccs.carleton.ca
> > Phone: (613) 523-7846
> > Fax: (613) 523-8486
> >