Speaking rate normalization across different talkers in the perception of Japanese stop and vowel length contrasts

Perception of duration is critically influenced by the speaking rate of the surrounding context. However, to what extent this speaking rate normalization is talker-specific is understudied. This experiment investigated whether Japanese listeners' perception of temporally contrastive phonemes is influenced by the speaking rate of the surrounding context, and more importantly, whether the effect of the contextual speaking rate persists across different talkers for different types of contrasts: a singleton-geminate stop contrast and short-long vowel contrast in Japanese. The results suggest that listeners generalized their rate-based adjustments to different talkers' speech regardless of whether the target contrasts depended on silent closure duration or vowel duration. Our results thus support the view that speaking rate normalization is an obligatory process that happens in the early phase of perception.