Examining acoustics and intelligibility of people with dysarthria in communicative interactions

Abstract

A comprehensive understanding of the speech capabilities of speakers with dysarthria requires an examination of speech produced in true interactions. Intelligibility in such interactions may reflect joint contributions of speakers and listeners (Olmstead et al., 2020). In this study, nine people with dysarthria secondary to amyotrophic lateral sclerosis (ALS) participated in an interactive word-matching task with nine typical individuals. In experiment one, we examined speech produced by the people with dysarthria in the interactive task and compared it to speech produced in two non-interactive tasks (baseline and clear speech). Specifically, we measured F1, F2, and vowel duration of the vowels /æ, ɛ, ɪ, and i/. We found task-related differences such that acoustic contrast was greater in the interactive task than baseline. Notably, speech in the interactive task was similar to clear speech in its spectral but not temporal patterns. In experiment two, we obtained perceptual judgements of these productions from 54 naïve listeners. We found a concordant pattern: the vowels from the matching task were easier for listeners to identify than baseline. Overall, results of these studies indicate that speakers with dysarthria can make speech adjustments in communicative tasks that are beneficial for listeners.