[LAD] Paul's Extreme Sound Stretch

fons at kokkinizita.net fons at kokkinizita.net
Thu Sep 30 21:16:32 UTC 2010

On Thu, Sep 30, 2010 at 09:23:08PM +0200, Robin Gareus wrote:

> Back when I was introduced to FT in some Physics lecture I was happy
> that I was able to use it and completely forgot to check the history :)
> Probably related to why I favored experimental Physics over Theory.

If you're still living in Paris, make sure to visit the 'Musée des
Arts et Métiers' one day. Quite a nice place for vintage experimental
physics. It's also the place where the final mad scene of Umberto Eco's 
novel "Foucault's Pendulum" is situated. The pendulum itself used to be
there, but it's now at the Panthéon.
> > And I guess this is where the windowing comes in. Calculate the spectrum
> > of small pieces instead.
> >
> correct.
> Furthermore there are different kind of windows (here a window refers to
> a block of audio-samples) and windows can overlap. That's where it gets
> complicated.

Even windows won't save you from apparent madness. Imagine a signal
consisting of all zero samples, except one every second which has
value 1. Such a signal contains all frequencies that are a multiple 
of 1 Hz, up to half the sample frequency. Those frequencies are present
all the time. Now take a window of say half a second. If it includes a
pulse you get more or less the same spectrum again. If it doesn't, you
get nothing... even if the frequencies should be there :-)



There are three of them, and Alleline.

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