ドナウエッシンゲン音楽祭
The period between 1947 and 1950 was one of intense compositional activity for Boulez. New works included the first two piano sonatas and initial versions of two cantatas on poems by René Char, "Le Visage nuptial" and "Le Soleil des eaux". In October 1951 a substantial work for eighteen solo instruments, "Polyphonie X", caused a scandal at its premiere at the Donaueschingen Festival, some audience members disrupting the performance with hisses and whistles.