Digital processing of instrumental sounds

In work at IRCAM (Paris), digital processing techniques were developed to alter pre‐recorded instrumental materials in perceptually novel ways. The goal of this processing was to create sound materials that were fundamentally unfamiliar but could co‐exist with natural instruments in muscially satisfying ways. (1) Because sounds are represented numerically for digital purposes, the potential for sound editing is changed qualitatively. Musical phrases were extended and transformed by replicating segments of them in ordered patterns whose structural properties dominated those of the original without eclipsing its identity. (2) Phase vocoding techniques were used to analyze instrumental sounds. Resulting data were appropriately reduced to form the basis of resynthesis through the MUSIC X program. In this way, independent access to arbitrary groups of partial components was attained. Odd and even partials were presented over spatially distinct speaker channels and subjected to dynamically changing vibrato functions with differing rates and depths. Additional distinct auditory images arose in the stereo field while the sonic image of the original instrument remained. Examples of instrumental recordings and their digital transformations are presented in isolation and in musical contexts.