Prosodic features in Finnish-speaking adults with Parkinson´s disease

The aim of this study was to assess prosodic features in Finnish speakers with (n = 16) and without (n = 20) Parkinson's disease (PD), as there are no published studies to date of prosodic features in Finnish speakers with PD. Chosen metrics were articulation rate (syllables/second), pitch (mean F₀) and pitch variability (standard deviation F₀), energy proportion below 1 kHz (epb1kHz), normalised pairwise variability index (nPVI), and a novel syllabic prosody index (SPI). Four statistically significant results were found: (1) energy was distributed more to lower frequencies in speakers with PD compared to control speakers, (2) male PD speakers had higher pitch and (3) higher syllabic prosody index compared to control males, and (4) female PD speakers had narrower pitch variability than controls. In this study, PD was manifested as less emphatic and breathier voice. Interestingly, male PD speakers' dysprosody was manifested as an effortful speaking style, whereas female PD speakers exhibited dysprosody with a monotonous speaking style. A novel syllable-based prosody index could be a potentially useful tool in analysing prosody in disordered speech.