Production and perception of rise time in the voiceless affricate/fricative distinction.

Rise times of voiceless affricates and fricatives were measured when the test material occurred in sentences, in isolated words, and in isolated nonsense syllables. As has been reported previously the rise times of affricates were significantly shorter than those of fricatives. Rise times varied with the type of test material and for all types of material were significantly longer than those reported by L.J. Gerstman [unpublished doctoral dissertation, New York University (1957)]. Differences in the way the previous measurements were made do not appear to explain the discrepancy. Because rise time varies with type of test material, no auditory sensitivity at a single rise time value can be responsible for the perceptual distinction between voiceless affricates and fricatives. This conclusion was also supported by the results of a perceptual experiment in which listeners were asked to label speech or nonspeech stimuli drawn from a continuum varying in rise time. Substantially different estimates of the category boundary were obtained when the range of rise times covered by the stimuli differed.