An Examination of the Effect of Natural Background Noise on Spontaneous Speech Intelligibility in Parkinson's Disease

By Mary Coleman, Communication Sciences and Disorders; Amara Yaeger, University of Wisconsin-Madison Advisor: Carrie Rountrey Abstract: Purpose: This study examined the effect of natural background noise (BNN) on conversational spontaneous speech intelligibility (C-SSI in persons with ParkinsonOs Disease (PD). BNN characteristics included intensity (DB-SPL), frequency in the human speech range (FREQSP), consistency (CONS), presence of human speech (HU), presence of electronic noise (ELEC). This project is a first step toward improving our understanding of BNN effect on C-SSI in persons with PD. Methods: 13 participants with PD and mild-mod hypokinetic dysarthria wore a recording device for 15 hours across 2 days. Recordings of the whole group and 2 clinically-relevant groups, low- intelligibility (LOWC-SSI) and high-intelligibility (HIGHC-SSI), were analyzed. Listeners transcribed 10 randomly selected sentences. Transcriptions were compared to a key for C-SSI. A 10ms clip in close temporal proximity to speech onset for each sentence was analyzed acoustically and visually for targeted BNN characteristics. Results: There was no significant difference between or within subjects between dB-SPL and C- SSI, however, HIGHC-SSI and LOWC-SSI groups responded differently to dB-SPL (p=0.00463). When dB-SPL increased, C-SSI increased for LOWC-SSI speakers but decreased for HIGHC-SSI speakers. Further examination of the characteristics of BNN taken together showed that C-SSI decreased with increased dB-SPL. CONS related to a decrease C-SSI for the whole group, but an increase for HIGHC-SSI speakers. No other variables were significantly related to C-SSI. Conclusions: Results suggest that BNN impacts C-SSI, and certain BNN characteristics may have different effects on speakers with PD overall. HIGHC-SSI and LOWC-SSI groups are impacted by BNN in different ways. Further research is needed.