Does Auditory Feedback Perturbation Influence Categorical Perception of Vowels?

Speech perception and production are bidirectionally related, and they influence each other. The purpose of this study was to better understand the relationship between speech perception and speech production. It is known that applying auditory perturbations during speech production causes subjects to alter their productions (e.g., change their formant frequencies). In other words, previous studies have examined the effects of altered speech perception on speech production. However, in this study, we examined potential effects of speech production on speech perception. Subjects completed a block of a categorical perception task followed by a block of a speaking or a listening task followed by another block of the categorical perception task. Subjects completed three blocks of the speaking task and three blocks of the listening task. In the three blocks of a given task (speaking or listening) auditory feedback was 1) normal, 2) altered to be less variable, or 3) altered to be more variable. Unlike previous studies, we used subject’s own speech samples to generate speech stimuli for the perception task. For each categorical perception block, we calculated subject’s psychometric function and determined subject’s categorical boundary. The results showed that subjects’ perceptual boundary remained stable in all conditions and all blocks. Overall, our results did not provide evidence for the effects of speech production on speech perception.