Lennie Tristano was a pianist and teacher at the Christiensen School of Popular Music in Chicago during the 1940s. A rigorous musical theoretician, he held a bachelor's degree in musical composition from the American Conservatory of Music. His use of timbre and rhythms pushed the cool concept into more atonal areas, combining polyphonic and polyharmonies, but keeping the basic pulse subtle. (b. 3/19/19 Chicago, d. 11/21/78 New York)