Pure tone auditory sequences were presented in a successive comparison task to Ss who were required to make judgments as to which sequence was longer. Experiment 1 was designed to test an hypothesis that sequences with small differences in frequency between adjacent tones would be perceived as shorter in duration than would sequences with large differences. Results did not support this hypothesis. Experiment 2 considered a systematic variation of the amount of frequency change in a sequence upon its perceived duration. These data indicated a direct relationship between perceived duration and the amount of stimulus change. A presentation order effect (POE) was found in Experiment 1 but not in Experiment 2 and it was suggested that the presence or absence of a significant POE was related to the ability of the S to store the sequences in memory.