The Instrumental Remodeling of Elements of Musical Electronics in Moon Veiled by Clouds

This article attempts to describe, in straightforward terms, an approach to composition based on the instrumental emulation of sonic techniques originating in the world of musical electronics. In the case of my own piece Moon Veiled by Clouds given here as an example, I acknowledge several precedents for various aspects of this approach. A short list of these would include Olivier Messiaen's Chronochromie (1962), Giacinto Scelsi's Konx-Om-Pax (1969) regarding the reinforcement of harmonics as an orchestration technique, Derek Bailey and Fred Frith as noted exponents of the prepared guitar, Karlheinz Stockhausen's Mixtur (1964), Gérard Grisey's Transitoires (1981), and Tristan Murail's Ethers (1978) in relation to the use of ring- and frequency-modulation models as a compositional resource.

The last of these pieces, Ethers by Mr. Murail, is particularly important in this context because, as Julian Anderson asserts in the sleeve notes to the 1992 Accord recording, it provides in its opening passage one of the very few examples of a single instrument standing as a metaphor for a ring modulation (RM) model. This is achieved in that instance by the simultaneous singing and playing of a note on the flute, which produces modulation within the instrument, resulting in a complex harmonic profile similar to that produced by ring modulation. The pitches of this "modulation" spectrum are then reproduced by the rest of the instruments in the ensemble in the more usual additive approach followed by the vast majority of "spectral" compositions.

Instrumental "Remodeling"

The exact manner of the instrumental representation of the ring- and frequency-modulation models in Moon Veiled by Clouds for gong, vibraphone, and prepared guitar, and in particular the remodeling of single-sideband modulation will I hope be of interest to those concerned with this field. The recreation of single-sideband modulation as it is presented here constitutes an additional metaphorical relationship that extends the pool of models used to date in spectral composition. The realization of this and other modulation models by manipulation of the spectral profile of a single stringed instrument also represents a variation on the spectral aesthetic that has almost exclusively relied on additive techniques realized by multiple instruments. The method used in Moon Veiled by Clouds to manipulate the spectral signature of the guitar is more akin to using various electronic modulation types to synthesize particular spectrum/formant profiles. Moon Veiled by Clouds focuses primarily on the re-creation, with conventional acoustic instruments, of three types of modulation: ring modulation (Black 1953), frequency modulation (Black 1953; Chowning 1973), and the less commonly used single-sideband modulation, sometimes referred to as frequency shifting (Bode 1967; Bode and Moog 1972).

The primary analytical tool used to facilitate the transference of these techniques from the electronic to acoustic worlds was the spectral analysis of a gong tuned to G-sharp and five of the strings of a prepared guitar. All spectral analysis was carried out with an FFT size of 65,536 with a uniform smoothing window that gives a spectral line resolution of 0.67 Hz. This of course allows relatively high pitch accuracy at the expense of rather poor temporal resolution, a compromise that was compatible with the use made of the spectral information in this piece.

Ring Modulation and Frequency Modulation

As Fletcher has noted (e.g., Fletcher 1978, 1993), woodwind multiphonics share many modulation features in common with ring and frequency modulation. A similar result can be obtained on brass and woodwind instruments by the simultaneous singing and playing of notes which gives rise to sum and difference tones related to the two initial pitches. The primary focus of Moon Veiled by Clouds was the transferal of this approach to a stringed instrument and the extension of this to single-sideband modulation. To achieve this, a procedure or technique had to be devised that would force a string to vibrate at two fundamental frequencies at once. To realize this, an artificial node had to be imposed upon the string that would encourage it to vibrate at lengths (and therefore frequencies) other than the naturally occurring...