isorhythm

Shepard tones

I've been struggling for a couple of weeks to decide how to end of this piece. I finally took a "just compose" course and started writing out notes. Soon I realized I was doing something like Shepard tones, so I thought, "Maybe I'll do this for awhile and then end it." Then I went through everything I had written up to this point and timed it. The passage shown below corresponds approximately to the jagged, angular section in the sopranos, beginning around 13:30. It ends about 15:30, but is just beginning to pick up some momentum at that point (haven't filled in everything yet in this picture). I began to realize that this could be the way I build to the end. It's a simple way to gradually layer repeated figures to thicken the texture. The timing is almost perfect. But the best thing about the Shepard tone* is its representation of circularity. Considering the selection of the text with its circular form, and that it will become intelligible as language during this passage, I think this is a bit of serendipity to have happened on the Shepherd tone.

Shepherd.jpeg

*) Of course this isn't a real Shepard tone, but it is a stylized approximation similar to the one found in Ligeti's etude "The Devil's Staircase."

Improvisation and beginnings

I've been playing with the free improvisation group Impulse on Saturdays for the past few months. I'd seen them play many times over the past few years, and I even created a computer program to improvise along with them in 2010, but playing piano with the group has been challenging and rewarding. They haven't had a piano in the past, so it's been interesting figuring out how that instrument fits in with their aesthetic (it's more percussive, less sustaining, and has a much greater range on the low end than the other instruments in the group). The reward for me personally is learning to trust my ear and also to listen to what's happening without trying too hard to force something. I'm hearing incredible sounds and textures that I wouldn't have discovered through my typical compositional processes. I keep catching myself being distracted from the moment, thinking how I can use this sound or that sound in my next piece.

The week before Thanksgiving we had a particularly interesting jam. At one point I was playing fast, steady, chromatic pitches within a one-octave span in the lower third of the keyboard. It was like a broken cluster, but only two notes at a time (one with hand), no patterns, and very rhythmic (regular durations but irregular accents). That evening I decided that's how to begin this dissertation piece.

The idea was hanging suspended in the middle-back of my mind, a bit uneasily because I was thinking of it as a kind of unrelated introduction that would give way to the actual piece. Tonight I finally realized how to make it part of the concept of the piece. The largest of the three sections will be the strings/winds section (joined from time to time by the percussion/piano/guitar group) which, later in the piece, will become engulfed in various circular isorhythms operating independently from one another. But I've always envisioned a very rhythmic and energetic opening that slowly gives way to a more Feldman-like texture. The energy of the "broken cluster" figure will drive the opening section. Occasionally the piano (which will be joined by the electric guitar and percussion here) will suddenly stop, and in the silence, the strings and winds will sustain the cluster's resonance, albeit with different colors. These sustained resonances will have jagged endings, followed by a return of the broken cluster. The rhythmic sections will gradually, and generally, get shorter while the resonances will get longer (although this will likely happen, as always, via a curve that will allow for regression from time to time). As they get longer, they will also begin to accentuate subset harmonies of the cluster resonance (like the held keys in "Filter-Schaukel" from Lachenmann's Ein Kinderspiel). Eventually (after four or five minutes), the rhythmic material will go away and isorhythms will begin to replace the cluster resonances. The textures and harmonies of the interactions of these isorhythmic parts will generate the form of the rest of this (the largest) section of the piece.

©2017 Joshua Harris