Phonetic convergence in shadowed speech: The relation between acoustic and perceptual measures

The current study investigates the influence of lexical factors on phonetic convergence and explores the relationship between acoustic and perceptual measures of convergence. A set of talkers produced baseline and shadowed tokens of target words that varied in frequency and phonological neighbor density independently. Experiment 1 demonstrated the impact of lexical factors on vowel dispersion in speech production. In Experiment 2, separate listeners judged the relative similarity of shadowed to model tokens in an AXB perceptual test of phonetic convergence. Acoustic measures of inter-talker distances in duration, fundamental frequency, and vowel formants for baseline and shadowed speech were compared to the perceptual measures. A mixed-effects regression model using a combination of acoustic convergence measures predicted perceived phonetic convergence better than lexical factors or individual acoustic attributes alone. These findings have important methodological and theoretical implications for understanding the complexities of phonetic convergence. Studies of convergence should consider examining acoustic and perceptual measures in tandem. Lexical factors impact speech production and perception, but their effects appear to be independent of those that evoke phonetic convergence.