Change in the pitch of a complex tone following its association with a second complex tone

The pitch of a high-frequency complex stimulus was changed and maintained in the direction of the pitch of a low-frequency complex stimulus with which it was associated. Six observers made pitch matches for a pitch-shift stimulus (1250-1450-1650 Hz) before and after simultaneous presentation of this stimulus with the first through fifth harmonics of 200 Hz (200-400-600-800-1000 Hz). Data were collected for each observer on five consecutive days and one week following the fifth day. The experimental phases each day were (1) ten matches, (2) simultaneous stimuli followed by ten matches, and (3) simultaneous stimuli followed by ten matches. Association periods for simultaneous stimuli were 5 min in duration and a 5-min rest period separated the association and matching periods. The result indicated that the pitch of the pitch-shift stimulus continued to change significantly for days one through four, from an initial pitch match near 210 Hz to a final match near 205 Hz. The post one-week pitch match was also significantly lower than the initial pitch match. The pitch changes are discussed in terms of a pitch learning hypothesis.