Klarinet Archive - Posting 000049.txt from 2010/08
From: Diego Casadei <casadei.diego@-----.com>
Subj: Re: [kl] Fundamental error on
Date: Thu, 12 Aug 2010 09:46:47 -0400
Dear Tony,
I said exactly the same thing as you, apart from the "No" :-)
The reed is the sound generator hence it cannot be a pressure node.
Cheers,
Diego
Tony Pay wrote:
> 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
--
Diego Casadei
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