An Unusual Effect in the Canon Per Tonos from J. S. Bach's Musical Offering

We propose that the phrase repetitions in the canon per tonos from J. S. Bach's Musical Offering are not recognized by listeners as being successively upward. We examine possible causes for this effect and suggest that it may be due to Bach's use of chromatic harmony. To test this hypothesis, we conducted an experiment in which one group of listeners was presented with Bach's canon, while another group was presented with a modified version of the canon in which the harmonies were altered in order to make the upward phrase repetitions more apparent. We found that subjects recognized the ascending pattern in the modified canon with greater ease than they recognized the ascending pattern in Bach's canon. We also consider briefly why Bach may have wished to cause such an effect.