LISTENER RATINGS OF EFFORT, SPEECH INTELLIGIBILITY, AND LOUDNESS OF INDIVIDUALS WITH PARKINSON'S DISEASE AND HYPOPHONIA

Hypophonia is a speech deficit observed in hypokinetic dysarthria associated with Parkinson's disease. This study investigated how multi-talker background noise affects listener ratings of effort, sentence intelligibility, and perceived speech loudness of individuals with Parkinson's disease and hypophonia and explored potential relationships among these variables. Ten individuals (8 women, 2 men; 18–43 years of age [M = 24.1; SD = 6.89]) were recruited as listener participants. Speech stimuli were obtained from audio recordings of 22 adults (17 men, 5 women; 58–80 years of age [M = 69.41, SD = 6.91]) with Parkinson's disease and hypophonia. These audio recordings were comprised of 13- to 15-word sentences from the Sentence Intelligibility Test (Yorkston, Beukelman, & Tice, 2011) read aloud in no added background noise and in 65-decibel multi-talker background noise. Listeners rated the intelligibility of the sentences using orthographic transcription, then rated the "perceived effort" expended when transcribing the sentences on a 100mm visual analogue scale. Listeners also rated the perceived loudness of the speakers with Parkinson's disease using a visual analogue scale. Paired samples t tests (p < .05) compared ratings of listener effort, sentence intelligibility, and ratings of perceived loudness across the two background noise conditions. Pearson correlational analyses determined the degree of correlation among listener effort scores, intelligibility scores, and perceived loudness ratings. Individuals with Parkinson's disease and hypophonia were rated to have less intense speech and reduced sentence intelligibility, and listeners reported significantly higher ratings of effort in background noise.