A source of pink noise

[Catalin C.]

Another one of my shareables that was waiting in queue...

Still on the technical side, as my musical sources need some further work.

Its beginning dates from the time I was testing the Freeverb circuit, so May-June 2019. It occurred to me that I should feed pink noise to the reverb and then pan it left-right while listening to spectral differences, as I was suspecting the signal treatment was different between channels (as it would have been revealed later, because of the 23sam issue) . So I put up a noise object, passed it through an LP filter and that was the source.

I might have been reading about the usage of pink noise in frequency response assessment by-ear at that time already. I was browsing PDF scans of "Modern Recording & Music" and other old audio publications. Fact is, I was doing something wrong and knew it, and it was all because of the hurry.

See, pink noise is defined as having all octaves carry an equal amount of energy, compared to white noise, and that is achieved with a faloff of 3dB/octave. Perceptually, all frequencies are heard at the same level, which serves the above mentioned scope.

Pink noise - Wikipedia

So it's far from enough to just LP-filter a white noise signal. We need complex filtering. After a couple of sessions with ABox, I've made a device I believe it outputs something close to math-generated pink noise. I've recorded the output and chose to compare it with Cool Edit 96's pink noise function.

Again one of my ideas, to make a bussed volume control so it can be moved freely around. It's needed, since continuous noise is not ear-friendly, even seeing as this device never reaches 0dB, therefore it's advisable to lower the volume when you're not focused on listening.

I don't know, maybe it could be bettered so that the top-end freqs also get represented. But that extra filter would require a steeper curve (L param. positive) and I don't know if it could avoid ringing. Also amps would need recalculation. As it is, the rolloff is no big deal.

It can also be used in sound design, e. g. in subtractive synthesis. The Minimoog(tm) and similar instruments feature a pink noise generator.

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This is it for now, I'll be back before holidays, hopefully with some nice gadgets.

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Catalin "Kirk" Chircan

[Keith W Blackwell]

I don't know why I never replied to this back when it was fresh, but since I'm catching up, let me just say thanks.  I've tried to put something like this together more than once and was never satisfied with the results.

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Keith