For a number of years, investigators have studied the effects one acoustic segment has on the perception of other acoustic segments. In one recent study, Miller and Liberman (Perception & Psychophysics, 1979,25, 457–465) reported that overall syllable duration influences the location of the labeling boundary between the stop [bl and the semivowel [w]. They interpreted this “context effect” as reflecting a form of perceptual normalization whereby the listener readjusts his perceptual apparatus to take account of the differences in rate of articulation of the talker. In the present paper, we report the results of several comparisons between speech and nonspeech control signals. We observed comparable context effects for perception of the duration of rapid spectrum changes as a function of overall duration of the stimulus with both speech and nonspeech signals. The results with nonspeech control signals therefore call into question the earlier claims of Miller and Liberman by demonstrating clearly that context effects are not peculiar to the perception of speech signals or to normalization of speaking rate. Rather, such context effects may simply reflect general psychophysical principles that influence the perceptual categorization and discrimination of all acoustic signals, whether speech or nonspeech.