Thursday, 14 August 2014

Ethereal Reflections

Reverberation Like Effects With Enveloped White Noise 

About half way through The Chase there is a pause where the sound goes very much more quiet and distant. This was a pure 'I wonder if that will work' moment for me. The effect was done not by a change in synthesis parameters, or adding an effect in the traditional sense - it the sound is nothing but an effect. It was done using impulse response reverberation using an white noise envelope.

convoll=sf.Multiply(sf.WhiteNoise(beat*4.0),sf.NumericShape((0,0),(beat*0.5,1),(beat,0.1),(beat*4,0)))
convolr=sf.Multiply(sf.WhiteNoise(beat*4.0),sf.NumericShape((0,0),(beat*0.5,1),(beat,0.1),(beat*4,0)))
left13 =reverberate(+left12,convoll)
right13=reverberate(+right12,convolr)

The Chase:
Normally we think of capturing an impulse response. We do this from recording in a space (an abandoned factory for instance) or from the output of a classic reverberation unit. How about designing one from scratch to produce exactly the effect we want?

I have continued with these ideas. Maybe the most extreme example is the use of 'diamond shaped' white noise signals in convolution for the stretch effect in Invasion:

rLen=20480
ns=sf.NumericShape((0,0),(rLen/2,1),(rLen,0))
convoll=sf.Multiply(+ns,sf.WhiteNoise(rLen))
convolr=sf.Multiply( ns,sf.WhiteNoise(rLen))

wleft =reverberate(left,convoll)
wright=reverberate(right,convolr)

Invasion:

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