In this article, the author presents structural analyses of Boulez's Second Study of Musique Concrète, Stockhausen's Gesang der Jünglinge, and Koenig's Klangfiguren II, focussing on the ways in which the composers have strengthened their articulation of form through the combination of timbres. The analyses are based on the composer's sketches and supported by graphic notations of their works.