Klarinet Archive - Posting 000946.txt from 2003/03

From: "Mark Charette" <charette@-----.org>
Subj: [kl] Clarinet overblowing an octave
Date: Sun, 23 Mar 2003 20:20:20 -0500

I posed the question of jumping an octave and some of my own hypotheses to
Dr. Joe Wolfe of the U of NSW (the keeper & author of that acoustics website
we've posted before). His answer:
----------------------------
Well we have a fair amount of experience with it, and we are still working
on it.

Roughly, the reed can play at its own resonance (loaded a little by
whatever is on either side of it). This is a squeak. However, if it is
damped (lips on it) and if there is a sufficiently strong resonance at a
lower frequency, it can be driven (nearly) at the frequency of that
resonance. It's actually rather difficult to answers to
- how strong must the resonance be
- how near must the resonance be
We're currently working on this and I shall put more up on the web later.

The impedance of a big diameter tube is low, and so its impedance at
resonance may not be enough to drive the reed. Similarly, when you open a
register key and weaken the low resonance, the reed jumps to a higher,
unweakened resonance.

Best
joe
Joe Wolfe School of Physics Ph: 61-2-93854954
University of New South Wales UT+10,+11 oct-mar
Sydney 2052 Australia J.Wolfe@-----.au
__________ http://www.phys.unsw.edu.au/~jw _________________

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