Re: Music Glossary - 1.64 Concert Pitch (2.12.2)

[Anthony W. Youngman]

In message <address@hidden>, Paul 
Scott <address@hidden> writes
> On Apr 3, 2009, at 3:49 PM, Anthony W. Youngman wrote:
>
> > In message 
> > <address@hidden>, Neil 
> > Puttock <address@hidden> writes
> > > 2009/4/3 Anthony W. Youngman <address@hidden>:
> > > > In message <address@hidden>, Anthony W. 
> > > > Youngman
> > > > <address@hidden> writes
> > > > > Ow!
> > > > >
> > > > > Sorry, reading this was painful (I play the trombone, as many of 
> > > > > you know
> > > > > :-)
> > > >
> > > > Replying to myself ... Just in case anyone didn't realise (and I 
> > > > certainly
> > > > didn't make myself clear :-) these are my revised versions that I 
> > > > think
> > > > should replace the existing entries. Feel free to edit and improve.
> > >
> > > > > For example Concert A is 440Hz, the speed of sound in air is 
> > > > > 343m/s,
> > > > > therefore an A clarinet (or any other A wind instrument) will 
> > > > > have a length
> > > > > of 343/440 = 78cm. (Or be a power of 2 longer or shorter.)
> > >
> > > Concert A is definitely not the fundamental for an A clarinet: it's a
> > > cylindrical tube stopped at one end, so the wavelength of the
> > > fundamental is four times the length.  Since the lowest note on a
> > > clarinet is usually the E below middle C unless it has an extension,
> > > the fundamental would be C sharp (D on a B flat).
> >
> > Ummm ... I think I might be getting physics fundamentals confused 
> > with musical fundamentals. But I'm COMPLETELY puzzled at your 
> > statement that the wavelength of the fundamental is FOUR times the 
> > length. I would guess the trombone is also "a cylindrical tube 
> > stopped at one end", and the wavelength of any note played must be 
> > an integral number of half-wavelengths. So we have 1/2-wavelength 
> > giving me a pedal Bb, 2/2 giving me the fundamental Bb, and 3/2   giving me an F.
> >
> > I don't see how the physics would work to give you a quarter- 
> > wavelength as you claim.
>
>
> I just did some quick online research and he is right.  A tube closed 
> on one end like a clarinet or trumpet has a wavelength that is four 
> times the length of the tube.  A flute is open on both ends so it has 
> a wavelength of double the length of the tube.

Okay, I've just looked up "standing wave" on Wikipedia, and it seems 
you're right about the "four times". I can't reconcile that with brass 
instruments though. The first four open notes on a Bb instrument are Bb, 
Bb, F, Bb. To me that's saying the wavelength is 1/2, 2/2, 3/2, and 4/2 
the instrument length, and NOT 1/4, 3/4, 5/4 and 7/4 (Wikipedia says 
that for a quarter-wavelength, only the odd numerators are available).

Can anybody explain?

Cheers,
Wol
--
Anthony W. Youngman - address@hidden