Klarinet Archive - Posting 000056.txt from 2000/08

From: Bilwright@-----.net (William Wright)
Subj: Re: [kl] Body movement
Date: Fri, 4 Aug 2000 13:09:20 -0400

<><> Neil=A0Leupold wrote:
Very interesting line of thought, Bill. Sound emanates all along the
length of the instrument via the tone holes. Making rapid and repeated
changes of physical orientation could possibly produce significant
differences to a listener. Is this a Dopler effect, or a consequence of
a shift in sound direction?

Just for the record, I mispelled Doppler's name the first time. But
getting serious for a moment:

There are a lot of assumptions about direction here because motion
perpendicular to the axis between audience and instrument does not have
the same effect as motion directly toward or away from the audience.
However I set my metronome to 60 beats/sec, and I found that I
could move the tone holes approximately 3 feet in one second and still
play a note without knocking my teeth out (double lip players may be
able to do better <smile> ).

Doing a bunch of 'worst case' math that includes the density of air
at STP (standard temperature and pressure), the speed of sound through
air of a particular density, and the speed at which the tone holes are
alleged to be moving, the change in pitch is a factor of approximately
0.9972.
That is, 440 hz would become 438.8 hz. When you consider that
orchestras argue over 440 hz vs 443 hz, the Doppler Effect could perhaps
make a noticeable difference under extreme circumstances!
If you do the same math and assume 4 ft/sec directly towards the
audience, the factor becomes .9960, and then 443 hz would become 441 hz.
I really can't imagine tone holes moving faster than 4 ft/second.

Cheers, (....well, you asked)
Bill

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