Instrumental synthesis
EN | FR
Instrumental Synthesis
by Julie Delisle
Timbre Lingo | Timbre and Orchestration Writings
Instrumental synthesis is a technique for composition and orchestration first developed in the 1970s. It is a founding principle of French spectral music, represented at that time mainly by the composers Tristan Murail, Hugues Dufourt, and Gérard Grisey.
This type of compositional process could not have existed without the technological progress in musical acoustics made in the previous decades. The invention that proved to be the most determinant is the sonagraph, a mechanical plotter coupled with an analog device that analyses recorded sounds. A sonagraph made it possible to get a visual representation of the frequency spectrum. For the first time in history, it was possible to visualize a sound and observe its various components. Since then, the process has been made more precise and powerful by the use of computers; nowadays, it is even possible to do it in real time.
This kind of visual representation of the frequency spectrum is called a spectrogram, and served as a basis for the composers of the spectral movement. These composers were aware of the scientific discoveries of their time about sound and music. In France, for instance, Émile Leipp and Michèle Castellengo’s work greatly inspired the composers who followed their progress, among them Gérard Grisey.
A spectrogram can provide a picture representing the frequency spectrum of any recorded sound. On this figure, you can see the spectrogram of a flute sound.
The color gradation (from red to blue) shows that the energy is concentrated in some regions of the graph, and the blue lines that can be observed correspond to partials of the flute harmonic spectrum (on a linear scale).
One could reproduce this flute spectrum electronically, by a process called additive synthesis, where a group of sinusoidal waves corresponding to the frequencies and amplitudes of each partial of the original spectrum are played simultaneously. Instrumental synthesis operates around the same principle and consists of taking a given sound with its spectrogram as a model, and approximating each of the partial (lines in the spectrogram) with notes played by acoustic instruments (or by different notes on the piano).
This is how Grisey created what he called “timbre-chords” (accords-timbres in French). One of the most fascinating aspects of this way of combining instruments is that the auditory system (the ear) hesitates between a segregation of each of the notes and the fusion that occurs almost automatically between the different sounds, creating a new emergent timbre.
As Grisey described it in his writings, instrumental synthesis “creates a hybrid entity for our perception, a sound that, without yet being a timbre, is no longer really a chord, a kind of mutant of contemporary music, derived from intersections between new instrumental techniques and additive synthesis realized with the help of computers.”[1]
If you would like to explore this kind of sound, see:
By Gérard Grisey, the Espaces Acoustiques cycle (1974–85, six pieces for ensembles of different sizes; part 1 : https ://youtu.be/jQgLU0gjPtI ; part 2 : https ://youtu.be/1BQQQ2bu3GM ).
By Tristan Murail, L’Esprit des Dunes (1994, for 11 instruments and synthesis sounds; https://youtu.be/ZFncet5VHRs) and Winter Fragments (2000, for 5 instruments and electronics; https://youtu.be/buv6oWx-wxA).
