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by Larry Polansky

Epitaph (Four Voice Canon #21) (tmfg)
Four channel tape piece

Study for Epitaph
Stereo tape piece

Notes on the use of MEAP software

Larry Polansky

Epitaph and Study for Epitaph are canons using my own guitar improvisations as subject matter, MEAP software, and some ancillary Java routines for "arranging". The source material is five guitar improvisations on fretless electric guitar, with a very limited set of materials (harmonics, glisses, open strings, etc). Each guitar part uses a different guitar tuning, based on harmonic series 1, 3, 5, 7, and 11. Each part is shorter than the previous, in the manner of a mensuration canon.

Each part is "sorted" in four different ways: by pitch, chroma, segment length, and a combination of centroid and spectral stability. Thresholds for segmenting are also varied in a particular way, so that successive voices (and sorts within voices) tend to have shorter segments.

The resultant 20 MEAPed edit-decision lists are then run through a few simple Java programs, to alter the start times of the canonic voices, and to impose a half-cosine interpolation loudness fade on each voice (using the gain() field of the edl). Successive "sorts" of each voice have slower fades, so that the four-minute piece is composed of 20 staggered and overlapping fade-ins.

In the stereo Study, these 20 voices are mixed in ProTools in such a way that each voice moves randomly in the stereo space, eventually settling in one of four locations in the stereo field. Each "sort" type has its own location. For example, the pitch-sorts for each voice end hard-left, the length-sorts hard-right, and so on.

In the quad piece Epitaph, four copies of each of the 20 EDL files are passed thru a Java program which performs the process above in a more formal way. By successively dropping out, in a stochastic fashion, events from selected channels of each of the (now) 80 source files, each of the four channels eventually ends up with the same sort for each of the five voices.

Thanks to Douglas Repetto and Dan Ellis for help with the piece, especially for adding features to MEAP to facilitate some specific needs. Thanks to Travis Garrison for some audio advice.

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