Score Sample

Recorded March 2, 2013 by Justin Gingrich and Dan Reifsteck, Harper Hall, Lawrence University. Percussion arrangement of my harpsichord solo, Monvillea (2012).

Orchestration: (2 percussionists), 2 marimbas, vibraphone.

Duration: approx. 7 minutes


The piece is very process-driven, but I used ACToolbox algorithms only in certain sections. The opening cannon is structured around an additive rhythmic process whereby one new note is added at the end of each repetition until m. 27 where the full rhythmic phrase is stated. The second marimba then continues the process in reverse—subtracting one note from the beginning with each repetition—until the transition at m. 51. Throughout, the music is exclusively in transpositions of Messiaen’s sixth mode of limited transposition, and voice leading is based on my reading of Christoph Neidhöfer’s paper “A Theory of Harmonic Voice Leading for the Music of Olivier Messiaen.”

In the middle section, I generated the lower voice of the ostinato part with an ACToolbox program. The notes of this lower voice perform a random walk. They are constrained by a certain minimum step size-that is they must move by step or leap only small intervals. This voice is also constrained to move within a certain maximum distance from the upper line and the lines may not cross. Later in this section, the intensification towards the climax was assisted by interpolating from the rhythmic ostinato of the middle section towards the straight eighth notes of m. 133. ACToolbox interpolated from (for instance) a rhythmic value of 3 (doted quarter) towards a rhythmic value of 1 (eight-note) via a countdown in time through all intervening simple decimal numbers. These values were then given a slight random deviation (from time vs. rhythmic value interpolation) and the result was rounded to the nearest eight-note. The effect is a smooth transition between rhythmic currents, but with a slight unpredictability.

The transition between m. 146 and m. 152 is an exceedingly simple process where a pseudo-chromatic scale coexists with a whole tone scale. This effect works better on the harpsichord, where I was able to have to two lines actually cross each other, creating unusual perceptual interference I believe. It still works on the marimba though.

mm. 153 though 179 are generated entirely in ACToolbox. Each of the lines here is a random choice of chromatic pitches between moving boundaries. That is, the computer is free to choose any note within a certain range, and that range changes over time creating a cascade of falling pitches. These pitches are then increasingly filtered using a pitch-class filter. As the section progresses any pitch note found in a certain transposition of Messiaen’s sixth mode of limited transposition is removed and a space is left in its place. A similar linier change govers the rhythmic material.

The final section is, of course, a return to the opening material.

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