Perceptual Tuning to Structure: Integrating the Phonetic Detail of Coarticulatory Vowel Nasalization With Prosodic and Information Structure

This study explores prosodically driven perceptual adjustment of a non-contrastive coarticulatory feature. Specifically, it examines how prosodic prominence and information structure influence the perception of anticipatory vowel nasalization in CVN in American English as a cue to an upcoming nasal consonant. Using a two-alternative forced-choice task, we tested whether the same acoustic degree of nasalization is interpreted differently depending on prosodic and information-structural contexts, and whether these effects are consistent across native English speakers and Korean learners of English. Listeners identified target words (Bob or bomb) from a nasalization continuum embedded in carrier sentences (“(No,) Riley wrote Bob/bomb slowly”), where the coda consonant was masked by noise. Prosodic prominence was manipulated by adjusting pitch and amplitude of surrounding words while keeping the target constant; and information structure was manipulated by including or omitting No, signaling contrastive focus. For a given stimulus, listeners gave more nasal responses (bomb) when the target was prosodically prominent or preceded by No, implying that they compensate for reduced vowel nasality in these contexts. The fact that No influenced perception independent of prosody suggests that information structure can modulate perceptual compensation beyond acoustic-prosodic cues, reflecting a top-down effect of discourse meaning. Finally, although Korean listeners gave fewer nasal responses overall—possibly due to reliance on acoustic detail or perceptual hypercorrection—both groups showed similar sensitivity to prosodic and information-structural cues. These findings taken together point toward a shared perceptual mechanism in both native and non-native perception that integrates fine-grained phonetic detail with prosodic and information-structural contexts.