Lexical Stress Production in Healthy and Apraxic Speakers of Australian English or French

features of apraxia of speech (AOS) include phoneme distortions and dysprosody. Descriptions of dysprosody have focused on lexical stress, specifically equalization of stress across syllables within words. However, lexical stress is a feature of stress-timed languages such as English but not syllable-timed languages such as French. This study aimed to make an acoustic comparison of lexical stress production in healthy and apraxic speakers of Australian English or French to ask whether measures of lexical stress are useful for AOS diagnosis cross-linguistically. Eight French (four AOS speakers and four control participants) and 18 Australian English (nine AOS speakers and nine control participants) speakers were recorded repeating 40 two and three syllable words that, in English, receive first or second syllable stress. All words occurred in both languages (e.g., habitat). The pairwise variability index (PVI) of vowel duration was used to quantify degree of variation across syllables within words. For each of the four word types, the AOS groups had lower PVI values than the control participants. Overall, AOS speakers had mean PVI values closer to zero than the control participants. Both control and AOS French speakers had PVI values closer to zero than that of Australian control participants. In conclusion, AOS speakers in both languages demonstrated signs of dysprosody at the lexical level with difficulty controlling relative vowel duration.