Klarinet Archive - Posting 000050.txt from 2010/08

From: Keith Bowen <keith.bowen@-----.com>
Subj: Re: [kl] Fundamental error on
Date: Thu, 12 Aug 2010 10:44:00 -0400

The difference between you is that Tony is right and you are "not"!

Do read the references he suggests.
It isn't very intuitive, but it is why a clarinet behaves differently from an oboe or flute(hence is an octave lower for the same tube length).

Keith

Sent from my iPhone

On 12 Aug 2010, at 14:46, Diego Casadei <casadei.diego@-----.com> wrote:

> 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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