Klarinet Archive - Posting 001145.txt from 1999/04

From: "Edwin V. Lacy" <el2@-----.edu>
Subj: Re: [kl] Glass Flutes?
Date: Wed, 28 Apr 1999 21:04:16 -0400

On Wed, 28 Apr 1999, Pat Flannery wrote:

> I found this on a trivia list. Does this make sense to anyone? What
> effect would humidity have on metal flutes (I can understand wood, but not
> metal)?
>
> >2. Glass flutes do not expand with humidity so their owners are spared
> > the nuisance of tuning them.

The effect of humidity on intonation doesn't result from any change to the
material, but primarily because of the effect of humidity on the ambient
air. Humid air is more dense, therefore sound waves travel more slowly
through it, resulting in lower pitch.

A more significant factor would be the effect of temperature changes on
both the air and the instrument. As the temperature rises, the air
molecules become more rarified, with the result that the pitch tends to
rise. But, in this case, there is an actual physical change in the
instrument. The material will tend to expand with a rise in temperature,
which should result in lower pitch. But, this effect is much less
pronounced than that which is the result of the change of the temperature
of the air. However, the change takes place at different rates in
different materials. The metal flutes will warm up very rapidly, because
the metals used are good conductors of heat. On the other hand, the thick
and dense wood of oboes and clarinets responds very slowly to changes in
temperature.

I know that glass is a very poor conductor of heat, so I should imagine
that it is relatively stable in changes of temperature.

So, the bottom line is, if your trivia item had concerned itself more with
temperature than humidity, I would have been more inclinded to agree with
it. As it stands, the statement seems to me to open up more questions
than it answers, and to ignore several significant factors. If I played a
glass flute, I expect I would want to tune it.

Ed Lacy
el2@-----.edu

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