Franges du Signe (1974) - Franges du Signe, the third part of an electroacoustic triptych completed in 1973-1974, is the first major "purely acousmatic" work composed by Guy Reibel. Franges du Signe explores the mathematical idea of the limit by translating it musically, searching for unstable states of equilibrium. Thus, several conflicting tendencies or logics act upon the sounds. They overlap and fight, each one seeking to assert its trace on the phenomenon in progress, generating de facto an ambiguity that is unique to all phenomena that obey the "logic of the living". Granulations-Sillages (1976) - Granulations-Sillages develops an idea glimpsed at in Franges du Signe: the existence of extreme times, at the edge of our faculties of perception, which only the electroacoustic music tools allow us to realise. Two natures of phenomena, opposed in all respects (the Granulations-Trails and the Tutti), alternate through seven movements that constitute the piece. The work is designed for six channels diffused in concert on a main stereo system facing the public and two auxiliary stereos (group of crossing speakers: front-back and left-right in the room).