spectrum inverting?

Mar 24, 2011 at 9:02am

spectrum inverting?

Hi -
I’m still getting acquainted with the fft~ objects and I was hoping someone might be able to offer some generous assistance in figuring out how to generate an inverted spectrum, within regular audible hearing range – so that frequencies at 0 hz would output at 20 khz, etc…

I apologize if this is redundant… I feel like there must be a fairly straight-ahead way of doing this..but I don’t have much of a mastery of this area yet..


Mar 24, 2011 at 3:52pm

invert the bins…

It might not sound as you think it should – our hearing range is logarithmic, the bins are not…

save as spectralinvert~

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and this is to test:

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Mar 24, 2011 at 3:55pm

You should also look into vocoder techniques…
Might sound better than fft…

Mar 27, 2011 at 11:13pm

last year i did an installation at the steim for amsterdams “sonic acts” festival inversing frequencies:


i wasn´t inverting the raw bins (that sounds dreadful) but using sigmund~ and its track feature and then doing a resynthesis. the remapping of the frequnecies happened there with the help of some scaling.
this sounded quite good.


Mar 28, 2011 at 1:09pm

or just ringmodulate your sound with mr. Nyquist (no need for fft)

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Mar 28, 2011 at 6:11pm

oh my god mr giri your mr nyquist idea is AWESOME! so simple! well for the mere mortals such as i, anyway. THAT should go in mr benson’s simple-stuff thread… thanks!

Mar 31, 2011 at 11:18pm

yes its the simplest solution, for sure.
but sounds ugly as hell :-)

thats why i choose sigmund~ back then


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