Clément Riot has produced, for the magazine écouter voir, a copious dossier on the 50 years (1948-1998) of concrete music. After having established a detailed history of the actors involved in this approach throughout history, citing influences in pop, rock and techno, he approaches three composers, acousmatic and polyvalent, to answer the same question: "what is composing on a medium? ». Among them, Denis Dufour, who has a very extensive instrumental repertoire, emphasizes his social approach to this type of composition with an immense cultural past. On the other hand, acousmatics is not based on any tradition, nor on any cultural or social code, but on a lutherie that opens up a universe of sounds without limits. In his mixed music, he likes to confront the two writings, the part on support and the score played by the performers.