 At 2 1/2 minutes long and focused primarily on density, "Concret PH" was created in the Philips office in Paris (Varèse having exclusive access to the studio with spatialization capabilities established in Eindhoven) or at the Groupe de Recherches Musicales.The only sound source is burning charcoal, cut into one-second fragments, with numerous transpositions and overdubs, a granular texture from which Xenakis creates a continuum.Using slight manipulation, the main techniques were splicing, tape speed change, and mixing.