It could be argued that Spectral Music began as an offshoot of the work being done by Jean-Claude Risset (b. 1938). Risset, French composer and mathematician, received his training under Mathews at Bell Labs between 1964 and 1969 and went on to become the first computer chef at Boulez’s IRCAM (1975–79). His research specialty was the matching and manipulation of recorded instrumental and natural sounds as a way of bridging the gap between the two mutually antagonistic worlds of early electronic music as described in chapter 4: the world of musique concrète, which made collages of “real” sounds, and that of the “tape studio,” where only electronically produced sounds were used. [Richard Taruskin. “Chapter 10 Millennium’s End.” The Oxford History of Western Music. Oxford University Press. New York, USA.]
The kinds of analysis done by Risset led to composers who wanted to blend the sonorities of acoustic and electronic music and create works using sound as their palette of source material. Melody was secondary, if evident, and harmony was non-functional. The primary aspects were timbre, or color, and texture.
This example, Barque Mystique by the composer Tristan Murail offers a glimpse of what spectral music sounds like.
What we notice is that the music does not use melodic motives, or harmonic progressions to establish phrases or periods. Instead what we hear are sound textures and gestures. When the instruments play fast passage work, it has the effect of arpeggiated chords and not as melodic content. The music has a somewhat static quality, and it appears that what the composer has in mind is an examination of the sounds for their own sake.
Another composer credited with establishing spectral music as a style is Gérard Grisey. Here is an example of his work Partiels, written in 1975.
The aspects of spectral music which are definitive can be seen as an outgrowth of music written much earlier than the 1970s, (the period when spectral music is loosely agreed to have become a genre in the wake of the work by Murail and Grisey, culminating with the terms “spectralism” and “spectral music” being coined by Hugues Dufourt in an article written in 1979). But composers as early as Claude Debussy, with his non-functional harmonic textures and exotic scales it could be argued that he planted the seeds for the music of spectral composers. More directly, composers Edgar Varese, Giacinto Scelsi, Olivier Messiaen, György Ligeti, Iannis Xenakis, and Karlheinz Stockhausen have all exhibited attributes that are the hallmarks of spectralism in their music at some point in their careers.
However, “in Spectral music, the first step of the composition process is the analysis of the sound with a spectrograph. Looking into the spectrogram, the composer can seize the characteristics of the timbre. Instrumental synthesis consists of using the orchestra as a mean to synthesise sounds. It basically features three types of models: instrumental harmonic spectrum, inharmonic spectrum and electronic music devices. The instrument model is the most current case: having first analysed the spectrum of a chosen instrument, the composer orchestrates the spectrum, i.e. he assigns the spectrum’s harmonics to every instrument of the orchestra.” [Justin Lepany, “Principles and techniques of Spectral music”, Cardiff University, School of Physics, Lecture: Sound Synthesis, Course Convenor: Professor Mike Greenhough, Spring Semester 2005.]
But the originality of spectral music does not come from the fact that it uses the overtone series. By 1850 the German physicist Hermann Helmholtz had discovered how the “color” of sound was influenced by the content and weighting of its overtone structure. Spectral music is singular and interesting because its practices respond to complex physical circumstances like the overtone series, rather than upon local and ad hoc stratagems such as are involved in building musical structures on the basis of a cell or a motif, as has been the dominant tradition in Western music.
This idea of rejecting the motif as the principal constituent element of a composition and of establishing timbre instead was posited by Grisey during a presentation at the Darmstadt courses in 1978:
The material derives from the natural growth of sonority, from the macrostructure and not the other way round. In other words there is no basic material (no melodic cell, no complex of notes or note values). [François Rose, “Introduction to the Pitch Organization of French Spectral Music”, Perspectives of New Music, Vol. 34, No. 2 (Summer, 1996), pp. 6-39.]
Composers continue to express their music in the spectral style, Murail and Grisey (until his death in 1998) continued writing new works, and composers such as Iancu Dumitrescu, Ana-Maria Avram write what is called hyper-spectralism. These composers will focus on dense choral textures, and repetitive drones, sometimes centering on a single note for several minutes.
The influence of the aesthetic school of Spectralism can be heard in the music of Philippe Hurel, Philippe Leroux, Marc-Andre Dalbavie, Jean-Luc Herve, Thierry Went, Fabien Lévy or Thierry Blondeau in France; Kaija Saariaho or Magnus Lindberg in Finland; George Benjamin or Julian Anderson in the United Kingdom, to quote only some of them, who draw much of their inspiration from the work of Grisey and Murail.
Composers use computer programs capable of sophisticated analysis of sounds to develop pre-compositional materials based on the spectral analysis of individual tones or timbres, i.e. the clarinet sounding the tone A. These programs are based on fast Fourier transform (FFT) and create charts that mathematically express a tone throughout a duration. These mathematical expressions can then be used to create hybrid timbres or as material to create the formal structure for a piece.
That said, in my opinion, the best way to appreciate spectral music is no different than that for any music: simply listen to it.
A very selected discography:
Tristan Murail ~ Gondwana / Desintegrations / Time & Again
Tristan Murail ~ Winter Fragments
Gerard Grisey ~ Les Espaces Acoustiques
Gerard Grisey ~ Talea; Vortex Temporum
Hugues Dufourt ~ L’Afrique & L’Asie d’après Tiepol