Klarinet Archive - Posting 000755.txt from 1998/02

From: George Kidder <gkidder@-----.edu>
Subj: Re[2]: Acoustics of the Primitive Early Clarinets
Date: Fri, 20 Feb 1998 10:20:53 -0500

Relative to partials: To a good first approximation, and by comparison with
other instruments (oboe), clarinets do not have even partials. To the same
first approximation, and with the same comparison, clarinets have a
cylindrical bore. Neither statement is completely true. Both statements
are simplifications, and as such are useful to organize our thinking.
Robert Howe makes a good case that the lack of stability of tone may be the
result of the (virtually) missing even partials, an explanations which seems
to make sense.

The acoustics experts tell us that to overblow at the 12th, a pipe must be
1) cylindrical and 2) closed at one end (and therefore show quarter-wave
resonance.) The clarinet approximates to both situations, and therefore
overblows at the 12th. It is acoustically closed at the mouthpiece end by
the mouthpiece and reed in a way that the flute is not. This alters "the
way energy is fed into the wave". But don't forget the oboe, which is also
closed at the reed end, and overblows at the octave because it is conical.
In other words, to produce the queer instrument we play, both 1 and 2 above
must be true. Fred Sheim is quite correct.

I am still puzzled by the empirical fact that both cornets (conical bore)
and trumpets (cylindrical bore) overblow at the octave, although both should
be closed pipes, with the lips taking the place of the reed and mouthpiece.
Anyone have any thoughts on this?

At 07:33 PM 2/19/98 -0500, you wrote:
>
>------------------------------
>
>Date: Thu, 19 Feb 1998 17:03:40 +0100
>From: Daniel.Meirsman@-----.com
>Subject: Re[2]: Acoustics of the Primitive Early Clarinets
>
>It is a though myth that clarinet sounds do not contain even partials. =
>A quick
>look at some books on acoustics of musical instruments could show you t=
>his (the
>Benade books are authoritative).
>
>Another myth is that clarinets overblow at 12th because of the cylindri=
>cal bore.
>Flutes have cylindrical bores. The reason clarinets overblow at 12ths a=
>nd flutes
>at 8ths is the way energy is fed into the wave. In one case it is at po=
>ints of
>greatest admittance in the other at the point of greatest impedance. In=
> other
>words the sound generating mechanism is responsable for the difference =
>(the
>'mouthpiece').
>
>Daniel
>

>
>Robert Howe
>------------------------------
>
>Date: Thu, 19 Feb 1998 16:09:39 -0500
>From: "Mr. Sheim" <fsheim@-----.com>
>Subject: Re: Re[2]: Acoustics of the Primitive Early Clarinets
>
>If I remember correctly, doesnt it have something to do with an open or
>closed ended pipe?
>
>Fred (fsheim@-----.com)
>