Compositional Models in Xenakis's Electroacoustic Music Author(s): Agostino Di Scipio Source: Perspectives of New Music, Vol. 36, No. 2 (Summer, 1998), pp. 201-243 Published by: Perspectives of New Music Stable URL: http://www.jstor.org/stable/833529 Accessed: 29/04/2009 05:54 Your use of the JSTOR archive indicates your acceptance of JSTOR's Terms and Conditions of Use, available at http://www.jstor.org/page/info/about/policies/terms.jsp. JSTOR's Terms and Conditions of Use provides, in part, that unless you have obtained prior permission, you may not download an entire issue of a journal or multiple copies of articles, and you may use content in the JSTOR archive only for your personal, non-commercial use. Please contact the publisher regarding any further use of this work. Publisher contact information may be obtained at http://www.jstor.org/action/showPublisher?publisherCode=pnm. Each copy of any part of a JSTOR transmission must contain the same copyright notice that appears on the screen or printed page of such transmission. JSTOR is a not-for-profit organization founded in 1995 to build trusted digital archives for scholarship. We work with the scholarly community to preserve their work and the materials they rely upon, and to build a common research platform that promotes the discovery and use of these resources. For more information about JSTOR, please contact [email protected]. Perspectives of New Music is collaborating with JSTOR to digitize, preserve and extend access to Perspectives of New Music. http://www.jstor.org COMPOSITIONALMODELS IN XENAKIS'S ELECTROACOUSTICMUSIC AGOSTINODI SCIPIO N IANNIS XENAKIS'SOUTPUT, electroacoustic music plays a role that is quantitatively marginal but quite meaningful in its content. In the fol- lowing observations, my aim is to demonstrate that highly relevant aspects of Xenakis's contribution to today's musical thinking are found in electroacoustic works like Concret PH (1958), Analogique A-B (1958- 59), and Bohor (1962), up to La Legend d'Eer (1977), Mycenae-Alpha (1978), and Voyageabsolu des Unari vers Andromede (1989), and most recently Gendy301 (1991) and S709(1994). PRELIMINARY OBSERVATIONS In electroacoustic music, compositional strategies are mediated by tools of work and thought-i.e., by a TxXvql(tekhne), an entire world of 202 Perspectivesof New Music techniques and technologies-often considered foreign to the field of the musicological discourse. However, this z?xvi( represents an essential expression of the knowledgewhich converges in the compositional pro- cess. As Pierre Schaeffer wrote, ". .. les idees musicales sont prisonnitres, et plus qu'on ne le croit, de l'appareillage musicale...."' The elabora- tion of the sound material and the strategies of musical design are cap- tured in actions, procedures, and tools which actually permit us to "record" and study the compositional process and to observe how the composer's ideas are transformed into audible musical objects. My analyses below lean on the notions of model of sound material, model of musical articulation, and control structure: * A model of sound material is the operative description of "compos- ing the sound." The analysis of electroacoustic music cannot waive the study of this aspect so essential to, and distinctive of, this type of compositional praxis. Characterizing a model of sound material shows the features of sound (microstructures) that are cognitively available to the development of musical form (macrostructures), and may illustrate the theory of sound implicit in the way in which the composer represents, conceives of, and works on and within the sound material. * A model of musical design is the operative description of "compos- ing with sounds." It illustrates the strategies of articulation of musi- cal form, i.e., the way in which the material is worked on and the way by which the overall form is developed out of smaller units and components. * A control structure represents the conceptual interface, as well as the operative link, between microstructures and macrostructures. It implements the relationship between the conception of material and the conception of musical form, and thus illustrates the features of material actually used (from among those available) in a certain musical construction. This approach helps us, I believe, to tackle questions that are funda- mental in music analysis:what is the material of the musical work under observation? By what methodswas the material worked on? How did this way of working finally bring forth the perceivedmusical structure? What relationship is there between sound and music? Thus, it becomes possible to grasp meaningful features of the music theoryand the aesthetic hypoth- eses underlying the work in question. Music analysis is understood here as a question of characterizing and evaluating the musical knowledge Xenakis's Electroacoustic Music 203 mediated by the z-XvTIin the process of composing, and the way in which such a mediation is accomplished.2 This is crucial as long as the particular tools for such a mediation are consciously chosen or even spe- cially designed by the composer-as in Xenakis's case. * * * Xenakis's work with electroacoustics has developed in two main phases: first, at Pierre Schaeffer's Groupe de Recherches Musicales, in Paris, from 1957 to the middle of the sixties; later, at the Centre Etudes Mathema- tique Automation Musique (CEMAMu), founded near Paris in 1966 by the composer himself together with mathematicians and researchers in computer science. Except for Analogique B (for tape, eventually superimposed on Analogique A, for strings), Xenakis's work at the GRM resulted mostly in pieces of musique concrete.I use the term here in its oldest sense (1948), pointing to a transformation of the compositional process: "... une inversion dans le sens du travail musical ... il s'agissait de recueillir le concret sonore, d'oui qu'il vienne, et d'en abstraire les valeurs musicales qu'il contenait en puissance."3 Bohor (eight-track tape) is an outstanding example of such an attitude, a powerful, compact, sonorous fresco more than twenty-three minutes long, delirious and violent in its materic magma. A relevant characteristic here is that this music is void of appar- ent phrase-like articulation, void of recognizable logical progression.4 This is perhaps explained by Xenakis's decision to focus on the potential for articulation in -rather than with-the sound material itself. I would like to illustrate this potential as explored in the composition of Concret PH and Analogique B-two works which, in rather different ways, both represent a mediation between the noisy violence of Bohor and the con- structive, mathematico-philosophical approach in Xenakis's instrumental works of the same period, such as Achorripsis (1956-57) and the computer-generated ST/10-1 (1956-62). FROM CONCRETPH . Concret PH (1958) is a 2'45"-long textural composition, a "cloud" filled with splinters of sound only vaguely differentiated among themselves. As is well known, this piece was conceived as an introductory event in Le Corbusier's Philips Pavilion, presented at the Brussels World's Fair in 1958 (the Pavilion also included Varese's only tape work, Poeme Electro- nique). 204 Perspectivesof New Music Sound design for Concret PH followed three steps. As a first step, the sounds of hot coals and burning material were recorded on tape. As a second step, very short chunks were extracted from the recording and isolated from their original context. Each chunk here corresponds to a single crackle, to a single creak of the coal in consumption-noise bursts lasting no more than a few hundredths (sometimes even a few thou- sandths) of a second. As is expected, such sounds have a very large spec- trum (see Example 1). Indeed, at this level the determination of frequency becomes dependent on the duration: the shorter the sound impulse, the wider the frequency band. (In other words, following Heisenberg's "uncertainty principle," a precise localization in the time domain causes indeterminacy in the frequency domain.) As a conse- quence, frequency and its perceptual attribute, pitch, are hardly control- lable here, as it is impossible for human ears to integrate differences of pitch and amplitude in such brief moments.5 As a third step, the short noise bursts were assembled to create a longer texture, by piecing together innumerable scraps of tape. A series of such textures was obtained, each having a particular temporal density dn = kn/At. Textures were then submitted to two distinct strategies of densification: 1. layering of m copies of the same texture: D = mdn (density of microevents controlled by means of a geometric series) 2. layering of different textures each with its own density: D = 2ndn. In both cases, the result of layering is a qualitative enrichment of the sound texture, heard as the fluctuating timbre of a rough dust of sound, with rare periodic patterns. In Example 2 readers can see a sonogram of the entire recording of Concret PH.6 Two types of texture can be distinguished, one made of very short noise bursts (wide frequency bands, with peaks at around 6000-9000 Hz), the other made of slightly longer bursts (narrower fre- quency bands, with peaks at 4000-5000 Hz). Often the two types over- lap, e.g., in fragments 40"-50" (Example 3a) and 110"-120" (Example 3b). Occasionally, one of the two is more in evidence-the first in frag- ment 30"-40" (Example 3c) and the second in the brief excerpt 80.9"- 86.6" (Example 3d) and later in fragment 100"-110" (Example 3e).7 Features found in large-scale spectral analysis are also found at smaller scales. For instance, Example 3c (fragment 30"-40") shows a sono- graphic snapshot which is quite similar not only to that of the entire piece (Example 2) but also to that of a very short detail only 0.3" long Xenakis's Etectroacoustic Music20 205 (Example 4, 37.7"-38").