Memory for a standard tone in comparison to a subsequent test tone was examined in three experiments with three intervening tones between the standard and test tones. In each trial, the intervening tones were presented from one of seven frequency range and distance from the standard tone conditions. Experiment 1 tone patterns were played at four different presentation rates, and the subjects judged whether the test was higher or lower than the standard. Memory interference effects caused by the different intervening tone conditions could be accounted for by a directional shift in the standard tone memory toward the intervening tones and by a general decrease in the standard tone memory strength with more distant intervening tones. Interference effects were smaller for the rapid presentation rates because the intervening tones formed separate "perceptual streams." Two additional experiments presented the tone patterns in a task requiring the subjects to match a continuously variable tone to their memory of the standard (Experiment 2) and a task requiring them to judge whether the standard and test tones were the "same" or "different" (Experiment 3). These experiments showed large differences in interference effects as a function of the required judgment and the subjects' musical experience.Memory for the pitch of a tone is disrupted when it is followed by tones of a different pitch. Deutsch and her colleagues have explored this effect in a series of studies which typically involved the sequential presentation of a standard tone, several intervening tones, and a test tone that the subject judged as "same as" or "different from" the standard (see Deutsch, 1975, for a review). In most of these studies, the effects of intervening tones were closely examined only for relatively small frequency separations from the standard and test tones (e.g., Deutsch & Feroe, 1975). This line of research has provided some important insights into the "microstructure" of intervening tone effects on pitch memory, but relatively little is known about the effects of larger intervening tone separations from the standard tone.The present series of studies tested the effects of intervening tones which ranged from 1 to 20 semitones above or below the standard tone. (One semitone is equal to a frequency difference ratio of about 1 : 1.06.) The experiments were designed to explore both the