Re: [Phys-l] frequency and wavelength of sound in air

[Brian Whatcott <betwys1@sbcglobal.net>]

John Denker wrote:
> ...
>  There is a wide class of audio systems that can be modeled 
> as "excitation plus filter".  This class includes the human voice, 
> reed instruments, bowed string instruments, and a few other things. 
[later you observed...]
>  you could play a violin in a room
> full of helium and it would not be appreciably out of tune.
In an interesting post, this contradiction of an earlier point was 
disappointing
and leads one into considering  the semantic niceties of saying "out of 
tune":
what does 'out of tune' mean?

In  human voice production, a helium inspiration does not set the vocal 
chords out of tune, either. But we are entranced by the transposition of 
familar voices into a higher octave.
Similarly (though I have not tried this  myself) I expect that a violin 
filled with helium might strongly accentuate the higher frequencies 
present in the spectrum excited by the bowed string.

Brian W