Spectralism emerged in France in the 1970s around the ensemble L'Itinéraire. Composers Gérard Grisey and Tristan Murail proposed writing music by analysing the inner structure of sound — its overtone spectrum — and turning that data into harmony and form.
Instead of discrete notes, the focus is timbre, microintervals, and the slow transformation of a sound mass over time. The landmark work is Grisey's Partiels, where an ensemble of 18 players “unfolds” the spectrum of a low trombone E. Spectral thinking, amplified by computer analysis of sound (IRCAM), became one of the most influential currents in contemporary art music.
