Influence of preceding fricative on stop consonant perception.

The effect of a preceding fricative on the perceived place of stop consonant articulation was investigated in a series of experiments. In experiment 1, we preceded synthetic syllables from two [tV]--[kV] continua with fricative noises appropriate to [integral of] or [s] and showed that more velar stops are perceived in the context of [s]. Experiment 1 also demonstrated a decrease in the magnitude of this perceptual context effect with increased temporal separation of fricative noise and CV portion, and with introduction of a vowel before the noise, which permitted a subjective syllable boundary after the fricative. Experiment 2 showed that although the effect of the fricative on stop perception declines initially with temporal separation, it may persist in reduced form over intervals as long as 375 ms. Experiment 3 replicated the basic fricative context effect using improved stimuli, but failed to replicate the reduction with an intervening syllable boundary obtained in experiment 1, which presumably was due to the vowel preceding the fricative. Experiments 4 and 5 revealed that the fricative context effect depends both on the phonetic category assigned to the fricative and on the specific spectral properties of the fricative noise. Experiment 5 also revealed a reciprocal effect of the stop consonant on fricative identification. We hypothesize that these perceptual effects serve to compensate for coarticulatory dependencies between stop consonants and preceding fricatives.