Klarinet Archive - Posting 000048.txt from 2010/08

From: Tony Pay <tony.p@-----.org>
Subj: Re: [kl] Fundamental error on
Date: Thu, 12 Aug 2010 09:33:20 -0400

On 12 Aug 2010, at 08:22, Diego Casadei wrote:

> Dear all,
>
> there is one big mistake on
> http://www.woodwindcourse.co.uk/user/image/clarinet_bore_design.doc
> which is worthwhile explaining here (few other details have been already
> commented by other people).
>
> In every wind instrument (*) the sound generator is just at the edge of
> the pipe which is controlled by the mouth. In particular, for the reed
> instruments the sound generator is the vibrating reed (or reeds for
> double-reed winds). This means that the clarinet reed exerts the
> pressure with the maximum amplitude on the column of air which is
> resonating inside the pipe.
>
> In diagrams like the drawing on page 4 of the document mentioned above,
> a "node" is a position along the tube in which the amplitude is minimum
> (ideally, it is null). The paper calls "antinode" a position which
> senses the maximum amplitude (**). Hence, the diagram on page 4 is
> clearly wrong: a node is not allowed at the reed position, because that
> is by definition the only certain place in which the amplitude is maximum.

No, the mouthpiece end of the clarinet functions like a closed tube, and so is a
displacement node (or a pressure antinode).

See Benade, or eg:

http://www.phys.unsw.edu.au/jw/clarinetacoustics.html#pipe

Tony
--

Tony Pay
79 Southmoor Rd
Oxford OX2 6RE
tel/fax +44 1865 553339
mobile +44 7790 532980
tony.p@-----.org

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