[LAU] organ stop

[Fons Adriaensen]

On Fri, Jan 20, 2017 at 04:28:11PM +0100, Jeanette C. wrote:

> Jan 20 2017, tom haddington has written:
> ...
> >The stop in question, the Vox Humana, can be heard at 1:27.  Apparently,
> >it's unique.  Can anyone please tell me a little about how this one works?
> >i hear a very early formant filter and am wondering just how this might be
> >mechanically accomplished.

> Hi Tom,
> it's not a formant filter. It's a reed pipe with a resonator. Wikipedia
> has this to say - and probably to show on the matter:
> https://en.wikipedia.org/w/index.php?title=Vox_humana

This *is* a what is called a formant filter in sound synthesis. It's not
a single resonance but typically two or three. What makes it a formant
filter is how it used: the intention is to boost some frequency bands
and attenuate others, but indepedent of the actual pitch. So the actual
strong harmonics depend on the pitch, but will always be in the same 
frequency bands which are typical for a particular vowel sound.

In a reed stop the pipe doesn't determine the pitch, it acts mostly
as a filter. Sizes and shape determine the actual filtering action.
I suspect that the ones heard in this recording are relatively short
(compared to a flue pipe of the same pitch) and propably have some
weird shape.


Ciao,


-- 
FA

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