EMUSIC-L Digest Volume 38, Issue 02 This issue's topics: Colored noise (8 messages) Your EMUSIC-L Digest moderator is Joe McMahon . You may subscribe to EMUSIC-L by sending mail to listserv@american.edu with the line "SUB EMUSIC-L your name" as the text. The EMUSIC-L archive is a service of SunSite (sunsite.unc.edu) at the University of North Carolina. ------------------------------------------------------------------------ Date: Wed, 4 Mar 1992 17:33:01 EST From: metlay Subject: Colored noise Does anyone know what green noise is? I know what white and pink noise are, but what's GREEN noise? (The Kurzweil 1000 series manual mentions several colors of noise as either soundfiles or modulation sources, and I got curious as to whether there was any basis for the coloration.) I THINK that the idea is to link frequency to color spectrum, so white noise is evenly distributed over all frequencies whereas pink noise follows a 1/f weighting so that you have equal power per octave, giving it more lows. I've heard of red noise, which is even more low-f weighted, and at least rumors of blue noise, which is high-f weighted. But GREEN? I'd really prefer official textbooks on acoustics to answer this question, but hey, idle speculation is fun too.... -- Mike Metlay metlay@minerva.phyast.pitt.edu Atomic City, P.O. Box 81175, Pittsburgh, PA 15217-0675 ------------------------------ Date: Wed, 4 Mar 1992 17:51:00 EDT From: RAY BROHINSKY Subject: Re: Colored noise Idle Speculation on green noise, huh? Well, I've seen a few interesting (if crack-potted) theories about color and light being related, and how all visible light fits within an octave of musical notes, just at a fairly high `pitch' 8^) I could guess that green noise (since green is in the center of the visible spectrum) is band-pass-filtered, and centered, either in the unlikely 20-20Khz range so often quoted, or more likely, centered around speech frequencies (which fall more closely to the center of useful fundamentals). On the other hand, if Kurzweil claims more than one such sample, I'd guess they are different roll-offs. (what's the use of talking about center freq. if you intend to use it with a keyboard?) Hey, if green noise is filtered so it's from the center of a spectrum, what would you call noise made from mixing the output of two BP filters, one high and one low? Purple? I know! PUCE! Puce noise! Wow, I'll patent it and make a fortune... in puce stamps!!! (apologies to Pogo...) raybro ------------------------------ Date: Thu, 5 Mar 1992 12:20:56 EST From: "Joseph D. McMahon" Subject: Re: Colored noise In article <9203042233.AA04638@minerva.phyast.pitt.edu> metlay@MINERVA.PHYAST.PITT.EDU (metlay) writes: >Does anyone know what green noise is? I know what white and pink noise >are, but what's GREEN noise? [...] > >I'd really prefer official textbooks on acoustics to answer this question, >but hey, idle speculation is fun too.... Groping back into the dim recesses of my memory when I actually thought I'd own an ARP 2600 some day... I recall that the "color" refers to where the spectral peak lands. Red peaks in the low frequencies, blue, in the high, and gree somewhere about the middle (on a log scale, of course). "Pink" is so called because the peak is in the "red" portion of the spectrum, but the 3 dB linear roll-off lends a lot of "white" coloration to it. And of course, none of this color talk has anything to do with "brown" noise, which is the world line of a two-dimensional particle undergoing Brownian motion... --- Joe M. ------------------------------ Date: Thu, 5 Mar 1992 13:55:51 EST From: metlay Subject: Re: Colored noise > > In article <9203042233.AA04638@minerva.phyast.pitt.edu> > metlay@MINERVA.PHYAST.PITT.EDU (metlay) writes: > >Does anyone know what green noise is? I know what white and pink noise > >are, but what's GREEN noise? [...] > > Green noise is the sound of money being extracted from your wallet when > buying another synth? > > -- Dave Knight > Truth is rarely as funny as it should be. |-/ -- Mike Metlay metlay@minerva.phyast.pitt.edu Atomic City, P.O. Box 81175, Pittsburgh, PA 15217-0675 ------------------------------ Date: Thu, 5 Mar 1992 17:00:47 GMT From: David Knight Subject: Re: Colored noise In article <9203042233.AA04638@minerva.phyast.pitt.edu> metlay@MINERVA.PHYAST.PITT.EDU (metlay) writes: >Does anyone know what green noise is? I know what white and pink noise >are, but what's GREEN noise? [...] > >I'd really prefer official textbooks on acoustics to answer this question, >but hey, idle speculation is fun too.... Green noise is the sound of money being extracted from your wallet when buying another synth? -- Dave Knight ------------------------------ Date: Fri, 6 Mar 1992 14:15:37 EST From: ronin Subject: brown noise brown noise is 1/(f^2) noise. i don't believe this characterizes brownian motion. i could be wrong. pink noise, for reference, is 1/f noise. btw... have you read that brownian motion might not be what brown actually saw? it seems that his apparatus was of sufficiently low resolution that it's unlikely he saw the molecular motion that bears his name, and was just seeing perturbations in the medium caused by his viewing conditons. -----------< Cognitive Dissonance is a 20th Century Art Form >----------- Eric Harnden (Ronin) or The American University Physics Dept. 4400 Mass. Ave. NW, Washington, DC, 20016-8058 (202) 885-2748 ---------------------< Join the Cognitive Dissidents >------------------- ------------------------------ Date: Sun, 8 Mar 1992 21:25:19 EST From: ronin Subject: brown noise redux oops, correction... i just looked it up. a one-dimensional brownian motion projected in time produces a waveform, described as brown noise, whose power spectrum is 1/(f^2). the term 'brown' is in fact a double entendre, since it refers, not only to the type of generative function, but also to the fact that brown light is 'redder' than white light. -----------< Cognitive Dissonance is a 20th Century Art Form >----------- Eric Harnden (Ronin) or The American University Physics Dept. 4400 Mass. Ave. NW, Washington, DC, 20016-8058 (202) 885-2748 ---------------------< Join the Cognitive Dissidents >------------------- ------------------------------ Date: Wed, 11 Mar 1992 15:07:26 EST From: ronin Subject: Re: Colored noise maybe green noise has formant characteristics. the blue would be a high end emphasis, and the yellow would be a boost in the lower mids. -----------< Cognitive Dissonance is a 20th Century Art Form >----------- Eric Harnden (Ronin) or The American University Physics Dept. 4400 Mass. Ave. NW, Washington, DC, 20016-8058 (202) 885-2748 ---------------------< Join the Cognitive Dissidents >------------------- ------------------------------ End of the EMUSIC-L Digest ******************************