Recursive Audio Systems: Acoustic Feedback in Composition
- Recursive Audio Systems:Acoustic Feedback in Composition
The following abstracts are summaries of articles that are available in full on-line in Leonardo Electronic Almanac. See the Leonardo Music Journal web site at mit-press.mit.edu/Leonardo/lmj/lmj13.html for links to the full articles.
Compositional and performance experience with a wide variety of audio feedback systems suggests a number of traits common to feedback processes. Acoustic feedback systems share certain sonic characteristics: whistling, melodically articulate resonances and gritty distortion. They also present unusual challenges for control and input, given their highly interdependent relationships between pitch, timbre, amplitude and time characteristics.
The authors discuss a number of compositions based around audio feedback. Christopher Burns's Letters to André and Calyx use interconnected digital effects processors as a homebrew waveguide network. Burns's realization of John Cage's Electronic Music for Piano simulates acoustic feedback in a software synthesis environment, creating a unique instrument in the spirit of Cage and David Tudor. Matthew Burtner's Delta, for electric saxophone, suggests the challenges involved in improvising with a highly unstable system. (Burt-ner's Study 1.0 (FM) is also referenced in the on-line article; this work is discussed in detail elsewhere in this issue of Leonardo Music Journal.)
In each of these projects, feedback system design was a major part of the compositional process, with the arrangement and configuration of the electronics determining the range of options for the pieces. Once the system is established, improvisation becomes an essential mode of compositional exploration. The unusual parameterizations of feedback systems, including their high degree of dependence upon the current state and contents of the system, necessitate an investigative approach. Improvisation may be used to chart a system's parameter space and likely responses prior to making compositional decisions (as in Calyx), or in the moment of performance (as in the Electronic Music for Piano realization and Delta). In either case, the composer/performer is likely to perceive him or herself as engaging with and influencing the feedback system, rather than commanding it. [End Page 73]
