With the development of digital signal processing (DSP) technology, a more subtle solution to the conceptual problem posed by musique concrète was developed. One exemplar of this solution is the work of Tetsu Inoue.
[caveat: this discussion is based on analysis of Inoue's work, not on any knowledge of his actual methods or thought processes.]
Tetsu Inoue is perhaps most famous for his ambient work, especially the albums Ambient Otaku, 1994 and World Receiver, 1996. This work (in particular World Receiver) often has a musique concrète flavor as it incorporates field recordings and other found sounds. Here, however, we will focus on Inoue's "sound sculpture" period, stretching roughly from 1998 - 2001, a period characterized by Inoue's move from the analog to the digital realm. The representative albums of this period are:
Psycho-Acoustic (May, 1998)
Waterloo Terminal (October, 1998)
Fragment Dots (May, 2000)
Active / Freeze (with Taylor Deupree) (July, 2000)
Object & Organic Code (June, 2001)
During this period, Inoue focussed more on short "sculptural" constructions, almost reminiscent of recent developments in free improv, than on the long, morphing textures of his previous ambient period (later work would combine aspects of both). The palette of sounds is quite divers, and it is often difficult to tell if a particular sound is generated digitally or is a digital manipulation of a found sound. Inoue clearly uses many different organizational principles; for example, Waterloo Terminal used the building (i.e. "Waterloo Terminal") itself as an organizational principle, inspiring Inoue to combine field recordings from within the space with sounds generated via a digital transformation of the terminal's blueprints into audio. Here, however, we consider Inoue's technique for importing the classical "theme and variations" structure into the realm of musique concrète, a task which seemed promising but problematic in our discussion of Pierre Schaeffer.
DSP provides a tool for manipulating subtle aspects of a sound: one can i) adjust the envelope (the rate at which the sound fades in and out, a manipulation powerful enough to turn a trumpet into a violin), ii) adjust the pitch ("Alvin and the Chipmunks" being a well known example (though most likely not achieved digitally)), iii) adjust the timbre (by selectively (d)emphasizing isolated frequencies, components of the overall sound, one can change it's character, turning a crowded room into a bubbling brook or a passing airplane into a pesky gnat), etc.
Of course, analog electronics could produce all these effects as well. What DSP offered was greatly increased organization, control, and memory of these parameters. At last composers could precisely specify the pitch to be filtered rather than find it by ear, they could store and "undo" manipulations, tweaking them until the desired effect was received.
In the Western tradition, a theme and variations consists of a melody and variations on that melody which tend to add or adjust the specific notes and rhythm played while maintaining the same basic chord progression. DSP opened the possibility of transposing this structure to the realm of musique concrète by taking a particular found sound (or sequence of sounds) as the "theme" and manipulations of its timbre as the "variations." This timbral "theme and variations" could then provide an underlying unity to the piece's organizational structure.
Consider this excerpt from "Cut and Clicks," the first track on Fragment Dots:
At 0:45-8 we can hear a sample of a running shower (presumably). This apparently unaltered sample is foreshadowed by a manipulation of the shower sound which integrates more closely with the surrounding bleeps and clicks at 0:05-0:07, and by brief spurts of a shower and a shower door preceeding the main sample at 0:43-5. At 1:11-2 we briefly hear the white noise of the shower again and from 1:35-end we can hear a succession of versions of the shower sound, each filtered in a slightly different manner (other segments may originate in this same sample, but have been manipulated too much to allow certain identification). For more local examples of variation via timbral manipulation, consider the patterns at 0:38-43, where the same fast vibration occurs at several different pitches and timbres, and 1:17-26, where the same rhythm is heard with three different timbres.
Of course, we have not by any means exhausted the organizational principles at work here. DSP also allows the composer to adjust a variety of source sounds such that they share a timbre, for example, and to closely control various permutations and arrangments of a predetermined set of sounds. "Cut and Clicks" surely evinces a variety of such techniques in addition to that of timbral variation.
Our final case study will examine an entirely different approach to the conceptual problem posed by musique concrète