excerpt from article by john a. maurer iv
June 4, 1999
"Chris Chafe's Push-Pull (on Chafe's Arco Logic CD, Centaur Records, 2001) for celletto and digital electronics is a good example of interactive electronic composition. It was composed in 1995 with the support of a National Endowment for the Arts (NEA) Fellowship.
...The tight interaction between cello and the live electronic parts in Push-Pull can be compared, I think, to Pierre Boulez's Repons, a landmark composition in the field of interactive electronics realized at IRCAM in the 1980s. Electronic transformations of soloists' sounds include time- and pitch-shifting, modulation (of each other), and rapid spatial movement, similar to the effects used in Push-Pull. The idea of "response" conveyed by the title is central to the piece and similar, too, to the meaning implied by "push-pull": the 24-member ensemble and various soloists respond to each other, and the soloists and computer system do likewise.
...Chafe's use of non-linear dynamic equations - i.e. chaos equations derived in the last 40 years from science's physical observations of the non-linearities in the natural world - to derive musical patterns with unpredictable and natural-sounding variation is one attempt being currently fashioned by many computer music composers to achieve such life-like responses."