I was going to try something similar, something like a MIDIquest 'random parameter' generator running into a few analog/virtual analog synths (MS2k, SY35, mopho, whatever else i see on Craigslist). Probably the most straightforward way to generate "harsh" noise (there's blue and violet noise, emphasizing above 1kHz, according to Brian Shepherd's synthesizer textbook) is to run random parameters into a Yamaha DX7.

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reminds me: need to read Vertical Color of Sound: http://www.amazon.com/Brian-Eno-Music-Vertical-Color/dp/0306...

also reminds me: someday I'm going to listen to Lou Reed's Metal Machine Music