[PD] fft -> get to know of requested frequency range

IOhannes m zmoelnig zmoelnig at iem.at
Fri Jul 23 16:02:41 CEST 2004

Christian Klotz wrote:
> On 23.07.2004, at 13:17, IOhannes m zmoelnig wrote:
> I am new to sound analysis and started using fft because I thought about 
> doing some other things with the sound analysis later. My problem is - 
> even after reading the fft documentation - that I dont know how to 
> handle the real and imaginary data. The main question for me is which 
> objects or arguments have to be set to check if the sound contains the 
> requestd frequency range.

probably try [bp~ 11000 100] (see help-patch for [bp~]; play with q)
then use [env~] to measure the power in the filtered signal.
most probably you will have to set the result into relation to the 
original signal somehow (to make it robust against loudness variance)

as for real and imaginary data:
|c| = sqrt(x^2+y^2)
now x and y are your signals; you most likely can skip the sqrt() as it 
is costy and only "scales" (non-linearily) the result.


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