Speech rate and prosodic phrasing interact in Korean listeners’ perception of temporal cues

Abstract

This study explores the interaction between contextual speech rate and prosodic phrasing in listeners’ perception of temporal cues in Korean. We investigate perception of the aspirated/fortis stop contrast, testing categorization of a Voice Onset Time (VOT) continuum. Aspirated stops have longer VOT and shorter vowel duration relative to fortis stops. There is a strong tendency for vowel durations in both stops to be lengthened at the beginning of a prosodic phrase, and this prosodic strengthening pattern has been shown to influence perception of the stop contrast with temporal context controlled. Building on this previous finding, we manipulate preceding speech rate in a carrier phrase (slower/faster) and cross this with a phrasing manipulation: 1) no prosodic juncture before the target, 2) a preceding intonational phrase boundary (cued by pre-boundary lengthening), and 3) the same boundary with an additional pause. Results show canonical speech rate effects only in the absence of a preceding boundary. Prosodic strengthening effects, which are additive based on boundary strength, are robust only when speech rate is slow. In sum, findings suggest a mutual influence between speech rate effects and prosodic phrasing effects, providing insight into the interplay of these factors in shaping temporal cue perception.