UC Berkeley composition Professor Edmund Campion, a co-director of CNMAT, said in a statement that Mr. Wessel “searched at the boundaries of music, insisting that the results inform our understanding of music while helping create music and inspire musical things.” Besides teaching, Mr. Wessel conducted key research into the psychology of musical listening, including the effect of musical timbre, or tone color, on a listener's perception. After conducting research and teaching at San Francisco State University and Michigan State University, Mr.