Edit] The Acousmonium

Schaeffer presenting The Acousmonium.

In 1966 composer and technician Francois Bayle was placed in charge of the Groupe de Recherches Musicales and in 1975, GRM was integrated with the new Institut national de l'audiovisuel (INA - Audiovisual National Institute) with Bayle as its head. In taking the lead on work that began in the early 1950s, with Jacques Poullin's potentiomètre d’espace, a system designed to move monophonic sound sources across four speakers, Bayle and the engineer Jean-Claude Lallemand created an orchestra of loudspeakers (un orchestra de haut-parleurs) known as the Acousmonium in 1974. An inaugural concert took place at the Espace Pierre Cardin in Paris with a presentation of Bayle's Experience acoustique (Gayou 2007, 209).

The Acousmonium is a specialised sound reinforcement system consisting of between 50 and 100 loudspeakers, depending on the character of the concert, of varying shape and size. The system was designed specifically for the concert presentation of musiques concrete based works but with the added enhancement of sound spatialisation. Loudspeakers are placed both on stage and at positions throughout the performance space (Gayou 2007, 209) and a mixing console is used to manipulate the placement of acousmatic material across the speaker array, using a performative technique known as sound diffusion (Austin 2000, 10-21). Bayle has commented that the purpose of the Acousmonium is to "substitute a momentary classical disposition of sound making, which diffuses the sound from the circumference towards the centre of the hall, by a group of sound projectors which form an ‘orchestration’ of the acoustic image"; (Bayle 1993, 44).