spectrum inverting?

crimeanwaters's icon

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..

Thanks,
Aaron

Tj Shredder's icon

invert the bins...

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

Max Patch
Copy patch and select New From Clipboard in Max.

save as spectralinvert~

Max Patch
Copy patch and select New From Clipboard in Max.

and this is to test:

Tj Shredder's icon

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

hans w. koch's icon

last year i did an installation at the steim for amsterdams "sonic acts" festival inversing frequencies:
http://www.flickr.com/photos/sonicacts/page5/

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.

hans

Maurizio Giri's icon
Max Patch
Copy patch and select New From Clipboard in Max.

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

pid's icon

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!

hans w. koch's icon

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

thats why i choose sigmund~ back then
hans