The composer-performer collective l’Itinéraire, founded in 1973 by Murail and Tessier, was the de facto platform for spectral music in France. This chapter shows how l’Itinéraire formed with the aim of establishing an organ for the music of the youngest generation of French composers, and how, with the demise of Boulez’s Domaine Musical ahead of the opening of IRCAM, l’Itinéraire fortuitously found itself positioned as the successor to that Parisian new music series, endorsed by Messiaen and recipient of a state subsidy. The chapter details how Grisey composed Périodes, a l’Itinéraire commission and the first work composed from his Les Espaces acoustiques cycle, and how Grisey attended the acoustics laboratory at the Université Paris VI Jussieu, where, alongside lessons in musical acoustics, he absorbed the work of Abraham Moles on the application of information theory to art. The chapter also shows how Murail began to incorporate the models of spectral harmonicity and periodicity into his music from Tigres de verre onwards, and it explores the relationship of these instrumental compositional techniques to the computer sound synthesis work of Risset and Chowning.

The book’s conclusion situates spectral music as a modernist musical movement. It shows how spectral music reprises many of serialism’s concerns, albeit on a more psychoacoustically accurate level. It relates the debates between Levinas and the other spectral composers to an older debate about formalism in art between Flaubert and Sand. Finally, the book concludes by situating Grisey as the founder of spectral music.

Spectral music as a distinct movement began in 1976, when, within a few days of each other, Murail’s Mémoire-érosion and Grisey’s Partiels were both premiered by Ensemble l’Itinéraire. This chapter explores how, driven by the theorist Dufourt, the young composers associated with l’Itinéraire developed a theoretical identity in contradistinction to Boulez and IRCAM. As well as detailing the salient qualities of Grisey and Murail’s music in this period, the chapter explores the diverse spectral music of Dufourt, Levinas, and Tessier. Dufourt’s works Erewhon, La tempesta d’après Giorgione, and Saturne engage with insights regarding sound related to his encounters with Risset and Chowning. Levinas’s works like Appels foregrounded sonic parasitism and a dramatic spectacle far removed from the more reserved forms of Murail, of which the chapter shows Levinas to have been at times a public critic. Tessier’s music in this period was expressionistic and explored electroacoustic resources. As well as detailing these various spectral sub-currents, the chapter explores the role of l’Itinéraire’s performers in helping to develop performing techniques adequate to the spectral writing.

The introductory chapter to Gérard Grisey and Spectral Music: Composition in the Information Age situates the book’s historical narrative by focusing on correspondence between Grisey and Dufourt in 1980 discussing what name they should give their common musical movement:’ spectral music’ or ‘liminal music’. This matter of naming indicates the compositional values the composers prioritised: movement over stasis, thresholds over states, psychoacoustic phenomena over traditional notes and pitches. The chapter then gives an overview of the book’s argument that spectral music developed from serialism through embracing information theory and developments in psychoacoustics and computer sound synthesis. Inasmuch as it arose in France but depended on developments that occurred at Bell Telephone Laboratories in the USA, spectral music was transatlantic in origin and signified a paradigm shift in musical composition.

By the end of the 1970s, the spectral composers were being invited to speak at the Darmstadt Summer Courses and were enjoying favourable press coverage in France. Recognising the need for a common epithet for their musical movement, they discussed a few possibilities: ’spectral’, ’liminal’, and ’vectorial’. This chapter explores, in turn, Dufourt’s concept of spectral music, which signified a compositional approach recognising and drawing on the microscopic scale of sound as the composer’s true material; Murail’s more technical vision of spectral music, and how, at IRCAM from the beginning of the 1980s, beginning with the electroacoustic work Désintégrations, Murail developed a sophisticated music drawing on computational resources; and Grisey’s notion of écriture liminale, a psychoacoustics-informed approach to compositional writing based on blurred statistical parameters and musical mutation. The chapter ends by detailing how the Darmstadt Summer Courses in 1982, at which the composers of l’Itinéraire gave a joint seminar, were the end of their common movement and the beginning of spectral music as an internationally known compositional attitude.