At this time many of Germany’s important composers met every summer in Darmstadt. The course was called Darmstadt Holiday Course for New Music. Stockhausen went there in 1951. There he performed some modern music and met important people such as the music critic and philosopher Theodor Adorno. He heard the music of Messiaen and, soon after marrying, he went to Paris to study with Messiaen. In Paris he met Pierre Boulez and Pierre Schaeffer who was working on musique concrète. He experimented with different sounds that percussion instruments can make, and he started composing electronic music. When he went back to Cologne he worked in a studio for electronic music where he studied communications theory. By this time Stockhausen, Boulez and Nono were the leading composers of avant garde or experimental music.