Exploring the influence of intonational structure on perception of contrastive vowel length in Tokyo Japanese

Abstract

A recent topic of interest in the literature is how intonational/prosodic structure influences speech perception. We test how perception of a phonemic vowel length contrast in Japanese is influenced by the implied prosodic position of a target sound in a carrier phrase, with the target drawn from a vowel duration continuum. Based on previous findings in English [Steffman, JASA (2019)], we predicted that listeners should require longer vowel duration to categorize a vowel as phonemically long when it is in phrase-final position, reflecting an expectation of phrase-final lengthening. We manipulated implied position by changing only pitch in a carrier phrase, as informed by Japanese intonational phonology. The carrier phrase was otherwise identical across conditions. Additionally, psychoacoustic effects of pitch on perceived duration are unlikely to influence categorization as predicted by the prosodic account, making this a good test case for prosodic patterns’ independent influence in speech perception and the processing of durational cues. Results will be discussed in terms other recent findings related to intonation and perception of duration, and implications for the interface of prosody and speech perception more generally.