Re: [Flightgear-devel] flyby volume (was: Doppler volume)

[gerard r. <gh...@gm...>]

On jeudi 22 janvier 2009, Melchior FRANZ wrote:
> * John Denker -- Thursday 22 January 2009:
> > On 01/22/2009 06:05 AM, Melchior FRANZ wrote:
> > > But it depends on the frequency pattern, no? So we'd need to
> > > analyze the spectrum ... time to use libfftw3.
> >
> > No, the 1/r^2 attenuation is independent of frequency.  No FFT
> > required.
>
> The law is the same, but the distances aren't. Lower frequency
> travels farther.

Not fully right. 
Only right when high frequencies  are  stopped by objects. Low frequencies 
could go over, and farther
The wider and the heavier  the objects are,   the lower the frequency may only 
go through.
If there is no object between the emissive sound and the recever/listener  the 
full  auditive band ( 20/20000 hz)  is traveling to the same distance.

> I don't think that's irrelevant. An automatic 
> calculation wouldn't know of which kind the sound is.
>
> m.
>




-- 
Gérard
http://pagesperso-orange.fr/GRTux/

J'ai décidé d'être heureux parce que c'est bon pour la santé. 
Voltaire