Aurora (for Kraig Grady)

Posted 15 September 2007, 14:43

Description

Dawn on Mount Meru. Inspired by the work and encouragement of Kraig Grady.

Duration: 3:04

Background & Technical Details

I’ve been listening to music by Kraig Grady recently, and decided that I wanted to start exploring some of the scales he’s been using, in particular the family of tunings he calls “meta-slendro”. At Kraig’s suggestion, I started with his article An Introduction To The Scales Of Mt Meru And Other Recurrent Sequence Scales. The meta-slendro scales are derived from numeric sequences found in Pascal’s Triangle, specifically the one Kraig refers to as Meru #3.

In this piece, I use a 7-note scale and a 5-note scale, which I built using Scala. I started with a 12-note “chromatic” scale built from harmonics 9 through 200 in the Meru #3 sequence, as Kraig recommends in his article. Then I used Scala’s “mos” command to derive various subsets. Of these, I chose a 7-note scale and a 5-note scale that both used generator 7. Of the two only the latter can be called meta-slendro, since slendro is a pentatonic scale. But I like the way they sound together.

For each scale, I wrote lines that consist of permutations of two-note chords, or dyads, within an octave. These lines are played by instruments that simulate the sound of Tibetan bells (using these handy tables of modal frequency ratios). The 5-note scale uses a sequence of 19 notes, played twice (once forward and once retrograde) for a long phrase of 38 beats. The 7-notes scale uses a sequence of 41 notes, played once forward. Played together, these phrases make a rhythmic ratio of 38:41.

Underneath are droney loops made mostly from notes that are present in the original 12-note scale but not in the 5- and 7-note scales, along with a chord build up from combination tones based on the interval 1.324717957/1 (1.324717957 is the number towards which the Meru #3 sequence converges).

Update #1, 16 Sep 2007:

I’d like to thanks Steven Yi again, not just for blue, which has become indispensable, but also for his Mode 6 and Horner/Ayers horn Csound instrument designs, both of which I adapted for use in this piece. Please listen to his music too, it’s wonderful stuff.

Update #2, 16 Sep 2007:

Thanks to some very constructive comments from Carl Lumma and Rick McGowan on the Making Microtonal Music list, I have added more gain to the sound files and re-uploaded them.

Copyright & Licensing

Copyright © 2007, Dave Seidel. Some rights reserved. This work is licensed under a Creative Commons Attribution License.

Files/Downloads

MP3 (7.3MB, 48K/16-bit, 320kpbs)
OGG (4.7MB, 44.1K/16-bit, 207kbps)
blue & Csound project files, Scala files (23KB)

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