According to a provocative theory set forth by Manfred Clynes [most recently in Cognition and Communication 19, No. 2 (1986)], there are composer-specific patterns of (unnotated) musical microstructure that, when discovered and realized by a performer, help to give the music its characteristic expressive quality. Clynes, relying on his own judgment as an experienced musician, has derived such “pulses” for several famous composers by imposing time-amplitude warping patterns on computer-sythesized classical music. To conduct a formal perceptual asessment of four such pulses, two sets of piano pieces by Beethoven, Haydn, Mozart, and Schubert, one in triple and the other in quadruple meter, each synthesized with each composer's pulse plus a “neutral” version, were obtained from Clynes and presented in random order to listeners of varying musical sophistication for preference judgments. The results show reliable changes in listeners' pulse preferences across different composers' pieces, which supports one essential prerequisite of Clynes' theory. However, there were some significant deviations from the predicted perference patterns. Possible causes will be discussed. [Work supported by NIH-BRSG.]