Out of sight, out of mind: The influence of communicative load and phonological neighborhood density on phonetic variation in real listener-directed speech.

Abstract

Some models of speech production propose that speech variation reflects an adaptive trade-off between the needs of the listener and constraints on the speaker. The current study considers communicative load as both a situational and lexical variable that influences phonetic variation in speech to real interlocutors. The current study investigates whether the presence or absence of a target word in the sight of a real listener influences speakers' patterns of variation during a communicative task. To test how lexical difficulty also modulates intelligibility, target words varied in phonological neighborhood density (ND), a measure of lexical difficulty. Acoustic analyses reveal that speakers produced longer vowels in words that were not visually present for the listener to see, compared to when the listener could see those words. This suggests that speakers assess in real time the presence or absence of supportive visual information in assessing listener comprehension difficulty. Furthermore, the presence or absence of the word interacted with ND to predict both vowel duration and hyperarticulation patterns. These findings indicate that lexical measures of a word's difficulty and speakers' online assessment of lexical intelligibility (based on a word's visual presence or not) interactively influence phonetic modifications during communication with a real listener.