Decorrelate signal
Jonas_h
Posts: 2
Hi,
I have a question I hope that you can answer. I want to create a design file which take an input signal and outputs it in two outputs. Instead of outputting it as identical signals I would like to \"decorrelate\" the signals. I know this can be done in some way but I am not sure how to do it. I have seen people mention all pass filters as the solution.
The usage for this is for small-room cinema use where I have multiple rows and want side surround speakers for each row. Each row will receive identical signal and all side surrounds for each row should be decorrelated to avoid comb filtering.
Looking forward to your responses!
I have a question I hope that you can answer. I want to create a design file which take an input signal and outputs it in two outputs. Instead of outputting it as identical signals I would like to \"decorrelate\" the signals. I know this can be done in some way but I am not sure how to do it. I have seen people mention all pass filters as the solution.
The usage for this is for small-room cinema use where I have multiple rows and want side surround speakers for each row. Each row will receive identical signal and all side surrounds for each row should be decorrelated to avoid comb filtering.
Looking forward to your responses!
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https://www.google.dk/search?q=decorrelate+audio+signals&oq=decorrelate+audio+signals&aqs=chrome..69i57j0.4052j0j7&sourceid=chrome&espv=210&es_sm=93&ie=UTF-8
And this: http://dafx04.na.infn.it/WebProc/Proc/P_280.pdf
I've been thinking about this more, probably more than I should, and this is what I've come up with. If you look at the Fourier transform (or really just it's properties), a time delay results in a phase shift. The amount of that phase shift depends on the frequency. That does not affect the correlation, and the correlation coefficient is still 1 between the two signals. Now, what happens if you apply a 180 degree phase shift to ALL the frequencies? Think reversing the polarity on your speakers. You get a negative correlation coefficient of -1 (same signal just opposite polarity). Finally, if you want to perfectly decorrelate these signals, you essentially randomly change the phase of the signal without manipulating the magnitude of the frequencies in it. Ths will give a correlation coefficient near zero.