INFLUENCE OF VOCALIC CONTEXT ON PERCEPTION OF THE [ J [ s ] DISTINCTION : II . SPECTRAL FACTORS

The posi tion of the category boundary along a synthetic [J J-[ sJ noise continuum depends on the following vocalic segment: When the vowel is [u], more "s" responses are given than when the vowel is [aJ. In Experiment I, we showed that this context effect disappears when the vocal ic portion is synthesized so as to contain no formant transitions. To dissociate the contribution of formant transitions from contextual effects due to vowel quality per se, Experiment II employed synthetic fricative noises followed by vocalic portions excerpted from naturally produced [) aJ, [sa], Uu], and [su]. The results showed strong and largely independent effects of formant transitions and vowel quality on fricative perception. Both effects were substantially reduced when a silent gap was inserted between the fricative noise and the vocalic portion, leading to perception of an intervening stop consonant; however, formant transi tions continued to affect fr icative perception even though they functioned now as cues to place of articulation of the stop. In this experiment, we provided additional evidence that the formant transitions following naturally produced [J] and [s] are different from each other in perceptually significant ways, and we also found a strong speaker (male vs. female) normalization effect in fricative perception. Surprisingly, the speaker effect, too, was reduced by the presence of a silent gap.