Klarinet Archive - Posting 000735.txt from 2004/07

From: "Lars Kirmser" <musictrader@-----.com>
Subj: Re: [kl] Material influence on sound...one more time
Date: Mon, 19 Jul 2004 14:01:49 -0400

As a point of clarification, I think that we may be in agreement as to the
affect that the relative surface (not mass) of a bore has on the damping of
the vibrating column of air. But this is irrespective to the material from
which the instrument is fabricated. We can duplicate the natural roughness
of wood on plastic clarinet bore, (as Wolff does on his bassoon bores) and
get a similar result to a more porous materials. At the same time, many
clarinet manufacturers specifically polish and seal the bore of their
instruments (mirroring the conditions of a smooth plastic bore). The result
of polishing and sealing a wood bore results in a condition essentially
identical to that of a highly polished plastic bore. Both plastic and wood
can be made to be smooth or rough. So, we are not talking about the
material, but relative finish.

Lars Kirmser

> This isn't quite true, Lars. Materials can _absorb_ energy without
> vibrating to a measurable degree themselves. Especially in the case
> where the absorbing material is massive in comparison to the energy
> supplied, it is reasonable to wonder whether the body of an instrument
> can absorb energy and hence affect the air column vibration without the
> instrument itself vibrating to a detectable degree.
>
> That is, the discrepancy between the air column's low energy and the
> instrument's comparatively huge mass can *contribute* to hiding what's
> really going on.
>
> Also, even if the clarinet itself doesn't vibrate to a measurable
> degree, perhaps the degree to which it reflects vs. absorbs energy can
> have a measurable effect on the air column's vibration.
>
> Some day, when I have built two barrels that are as close to identical
> as possible, and both of them have a drastically larger outside
> diameters than a barrel is supposed to be, I intend to cut one of them
> down to considerably undersized and then listen to the pair of them. I
> may even try to find someone who will graph their acoustic spectra for
> me (when played by someone with a more stable technique than I have)
> before I cut one of them down.
>
> Morrie Backun or Walter Grabner or Clark Fobes all have the boring
> equipment to try this. I know that at least one of them has CNC
> equipment and can probably do this experiment more precisely than I can
> with my kluged-together-on-the-cheap equipment. I've often wondered
> why one of them hasn't done so and announced the results.
>
> It's not clear to me whether such an experiment would be most revealing
> when playing only mouthpiece+barrel vs. with the entire instrument, or
> perhaps boring a pair of unadorned (no tone holes) tubes and attaching
> them, one at a time, to the same mouthpiece or to a whistle's fipple.
>
> ....but the bottom line (imo) is that measuring how the instrument's
> body does or doesn't vibrate does *not* tell the whole story, and this
> is the major loophole in Benade's measurements.
>
>
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