Effortful listening during dysarthric speech perception despite accurate recognition

This study aimed to assess the effect of dysarthria presence and phrase recognition accuracy on listening effort, indicated by pupil dilation and perceived listening effort (PLE) ratings. Thirty-four listeners completed a speech perception task while an eye-tracking camera monitored their pupil dilation. Phrases in the task were spoken by a speaker with dysarthria secondary to ALS and a neurotypical speaker. Listeners then repeated what they heard and rated PLE on a 7-point Likert scale. Phrase repetition accuracy (correct vs. incorrect) was determined based on their verbal responses. Generalized additive mixed models (GAMMs) evaluated the effect of speaker status and phrase repetition accuracy on pupil dilation. PLE ratings were analyzed using linear mixed-effects (LME) models. Both pupil dilation and PLE ratings were higher when listening to the speaker with dysarthria compared to the neurotypical speaker, even when the phrase was perceived accurately. Phrases perceived incorrectly were associated with greater pupil dilation and higher PLE ratings than correctly perceived phrases. Interaction effects between speaker type and phrase repetition accuracy were found for pupil dilation, but not for PLE ratings. These findings suggest that listening effort increases overall when listening to a speaker with dysarthria, even if intelligibility is maintained.