[Phys-L] Re: sound frequency in helium

[Brian Whatcott <betwys1@SBCGLOBAL.NET>]

At 12:03 PM 4/24/2005, John M.,  you wrote:

> /// In speech, it is the (fundamental) frequency (of a
> complex waveform) that is primary.  In pipes it is the wavelength
> that is primary.
///
> John Mallinckrodt        mailto:ajm@csupomona.edu
> Cal Poly Pomona          http://www.csupomona.edu/~ajm

I was talking to the organist this morning. He is an organ maker.
I mentioned BC's observation that he had set a pipe a fifth higher
to sound with a low pipe. Tom Cotner remarked that setting a
  10  2/3 ft (?)  pipe to sound with a 16 ft pipe is a way to present
much of the effect of a 32 ft pipe, the 'resultant' as he called it.
The ear responds to the envelope of tones and can interpret them
as the 2nd and third harmonic of the (absent) bass pipe.

  He describes some other textural effects, like tuning a set of pipes
  justly, and tuning a second set just sharp, so as to present a pleasing
beat - this is a "celeste" effect, if I recall.     In synthesized organs,
makers take the effort to introduce microscopic variation of
tone and amplitude for the sake of 'realism'.  This sort of variation
is a more natural consequence of variation in sound chest pressure
depending on the notes demanded at the keyboard.

So, it turns out that with pipe organs, as with human speech one analyzes
the waveform envelope to deduce the tonality.



Brian Whatcott    Altus OK    Eureka!
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