The composition takes advantage of certain features of the FM algorithm which made it possible to integrate a non-tonal division of the frequency space and the ratio of non-harmonic spectral components. Several levels of the piece are governed by the ratio of the Golden Mean: the microscopic elements of timbre (the ratio of the partials), the ratio of the pseudo-octaves (which are not real octaves, but here the pitches and their partials an "octave" apart behave the same way pitches and spectral components of harmonic sounds in the spacing of real octaves do) and the overall form and development. Thus the sounds were not composed simply as spectra determining "timbre", but rather for functional purposes as well.
Thus, the harmonic relationship of simultaneously sounding pitches yield a certain transparency and order in what are normally considered "clangorous" sounds. – STRIA was commissioned by the Institut de Recherche et de Coordination Acoustique / Musique (IRCAM), Paris, which Pierre Boulez started in 1975 with the initial help from CCRMA, for presentation in Luciano Berio's exhibition of electronic music at IRCAM in the October of 1977.