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Law of Octaves
Posted 15 July 2008, 02:10
A waking dream — an
empty bowl by a still pond
lit by the full moon.
Second Sleep returns to the harmonic material I first started exploring in Aurora. In this piece, I move from one pentatonic scale (introduced as a slow, rising arpeggio and prolonged as a chordal drone) to another pentatonic scale, and back again. The continuous background drone consists of the “root” (1/1) pitch shared by both pentatonic scales, along with three other pitches that do not appear in either of the scales.
The first pentatonic scale (expressed as ratios) is:
1/1 9/8 151/128 3/2 25/16
The second pentatonic scale is:
1/1 37/32 21/16 49/32 7/4
The drone is built from the pitch set
1/1 65/64 43/32 57/32
The pentatonic scales/chords use a modified version of a Csound/blue instrument called Resonant Rhythm by Atte André Jensen. Atte describes his instrument as an “animated, resonant pad/drone/bass instrument with tempo sync”. As he designed it, it produces a steady pulse at a given rate, with randomized filtering applied to each successive note. I modified it for my own nefarious purposes in a couple of different ways:
In all instances of the modified Resonant Rhythm (MRR) instrument, I used a pulse-width modulated square wave.
Parts of the background drone (1/1 in three octaves) also use the MRR instrument. The other three pitches use a Risset harmonic arpeggio instrument with a waveform built from the the first eleven harmonics from the Fibonacci sequence (i.e., 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, and 144).
Copyright © 2008, Dave Seidel. Some rights reserved. This work is licensed under a Creative Commons Attribution License.