I have a processing unit that does a nice EQ filtering on soundfiles. The only thing I can do is : I give the original .wav file, and the processing unit gives me back the filtered .wav. I have no other information than this.
I'd like to know the frequency response graph of this processing unit. How to do it ?
1) feed the unit with a "flat spectrum white noise", and see the spectrum of the filtered file? It works but it is not very accurate
2) feed the unit with sinewaves soundfile with frequency = 20, 30, 40, 50, etc... 20 000 Hz. Then I examine the response for each file... and I can draw a frequency response graph after 10 hours of work :)
3) feed the unit with a frequency sweep ? and then try to see what's the unit's reponse to this sweep ? How to decode the response into a nice frequency response graph ?
4) I imagine that there is another better solution?