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The article Techniques for Polytemporal Composition by Christopher Dobrian was presented at the Annual Conference of the Korean Electro-Acoustic Music Society, Seoul National University, Seoul, Korea, on October 27, 2012.
It is provided here in PDF format as it appears in the conference proceedings (with some errors corrected). It is also provided in HTML format with links to working example versions in Max of the programs illustrated in the article.
Techniques for Polytemporal Composition (PDF) by Christopher Dobrian
Techniques for Polytemporal Composition (HTML) by Christopher Dobrian
Hemiola with audio loops - Figure 5: simultaneously played loops of the same sound, with loop lengths in the ratio 13:14:15:16, creating a constantly evolving relationship between the four loops. Illustration and Max Program File
Flexible, related tempi - Figure 6: simultaneously played patterns of notes with tempi in the ratio 3:4:5, creating a constantly evolving relationship between the three melodies; the three transports are synchronized to a single master tempo. Illustration and Max Program File
Rate change in audio playback - Figure 7: emulation of the phasing effect in Come Out by Steve Reich; the same sound is looped each audio channel, with a rate discrepancy of 0.15% (a ratio of 0.9985:1). Illustration and Max Program File
Timepoint mapping - Figure 10: constant-rate timepoints in one voice are used to look up timepoints for another voice in a non-linear transfer function; the use of straight line segments results in discrete tempo shifts depending on the slope of each line segment. Illustration and Max Program File
Gradual timepoint mapping - similarly to Figure 10 above, constant-rate timepoints in one voice are used to look up timepoints for another voice in a non-linear transfer function; the use of a curved transfer function results in gradual tempo changes (accelerandi and decelerandi) which depend on the curvature and the location relative to the central "unity" tempo. Max Program File
Minimal loops - an automated player of melodic loops of different lengths, in "minimal" style; periodically, a different length segment of a table of stored pitches is chosen and looped. Max Program File
Time-tagged samples - within a sound file, specific desired sounds can be identified, and their start and stop times stored; those sound objects can then be quantized or synchronized to specific timepoints in a video, and they will therefore stay in sync with the video even if its rate changes. This segmentation and time-tagging process is similar to that used in REX-formatted audio loops. Max Program File
Audio playback rate warped by a transfer function - similarly to the way that transfer functions are used in the above examples to warp timepoints, a transfer function can be used to warp playback speed of an audio sample; the effects can be subtle or extreme, depending upon how much the curve of the transfer function deviates from a straight line. The curve of the first preset in this example is fairly subtle, but the remaining presets show radical distortion of the playback speed.Max Program File
Whitney Music Box by Jim Bumgardner - a web application demonstrating, with animated graphics and sound, 48 to 120 separate harmonically-related tempi.
This site is written and maintained by Christopher Dobrian
This page was last modified October 29, 2012.