Sunday, February 10, 2008

Adventures in Sonification

I'm taking the last of the seminars required for my music MA this quarter - a class in computer music composition, as in Serious Art Music rather than just how to use midi or how to create the kind of electronica that's actually popular with listeners. This is really not a type of music I enjoy aesthetically. No matter how interesting the theory may be behind it, or how well the composer may write about his own piece, most of the pieces I've actually heard from this genre (and all of the ones we've listened to in this particular class) just haven't appealed to me, or have made me really want to turn the music off. (The ones I want to turn off, coincidentally, are the ones the professor declares as particularly beautiful to his ear.)

But for this seminar, I have to write that type of music. It makes sense, I suppose, as part of a thorough education for an academic composer, but it still wasn't appealing to me even when I thought I was going to be an academic composer. Yet at the same time, there's something liberating about being required to produce music in a style I know I won't want to listen to - I end up stressing over the sonic outcome less, which gives me more of an opening to mess around with concepts that are intellectually appealing (read: geeky) and not have to dismiss any of them for not sounding like I'd hoped they'd sound.

The way the assignments have been going so far is that the professor gives us a pre-constructed patch in a sound synthesis program called Max/MSP, and we have to tweak the parameters to produce different sounds from that patch, which we then record and toss together into a brief piece. Last week, the main patch we worked with involved drawing sound envelopes onto a grid, picking a speed and amplitude, then running a sine wave through it.

Last week also happened to be the week when our mineralogy class got the tour of the department's various microscope facilities. Coming from spending time the previous night drawing squiggles on the envelope grid in Max/MSP, the graphed output from powder diffraction looked an awful lot like some of those sound envelopes. The next course of action for the music homework seemed obvious.

So, I made five very basic "igneous sounds" (granite, granodiorite, diorite, gabbro, and peridotite). The patch only had two overlapping envelopes, so I couldn't include every mineral in each rock, only the two predominant components. Max/MSP gives you the option to program in very specific points on the envelope, so I could have made exact matches between the powder diffraction graph and the envelope, rather than drawing in an approximation as I actually did; the reason I didn't go exact is because I knew the professor would take all of two minutes to look at it, so time that could have been spent on specificity here was better spent elsewhere, such as on actual mineralogy, or on my thesis. I based the envelope amplitudes on the percentage of that mineral in the whole rock (for the "granite" sound, I set the amplitude for the "orthoclase" envelope at 500 and the "quartz" envelope at 200), though I experimented a little bit with how to show the percentages (the "diorite" sound had the "plagioclase" envelope at 170 and the "amphibole" envelope at 120). I didn't have any rhyme or reason, though, for the amount of time I told the program to take to play through the envelopes. I varied those because the professor assigned us to make sounds of different lengths. Now that I think about it, I could have determined the speed based on viscosity, or I could have differentiated based on speed of cooling, playing the felsic envelope quickly for rhyolite and slowly for granite.The rhythms created by the overlapping envelopes were pretty interesting, particularly for the slower sounds, and the pitches turned out surprisingly consonant/tonal. (Too consonant for my professor's taste, it turns out. He remarked on how "harmonic" it was, then made the next week's assignment involve only unpitched sound.)

I came into the first meeting of that music seminar wondering how I might be able to bring geological stuff into those assigned compositions, and I'm pretty pleased with how this tweaking of envelopes worked out. All the more incentive to try and come up with further ways to do so, as I learn more computer music techniques, not to mention more about the science I'm trying to portray with those sounds.

3 comments:

Maria said...

This is fantastically cool. Any chance you'll post a sample for us to listen to?

BrianR said...

I second that...this is fascinating. I'm very interested in hearing more about this project as you do more. Yeah...if you can figure out how to post mp3s...that'd be cool.

MJC Rocks said...

OK, the header on your blog literally dares us to insert "rock music" joke, so here it is. Not only is it rock music, it is hard rock, not that soft sedimentary stuff....

Sorry, I couldn't help myself...