Modeling fundamental frequency dynamics in hypokinetic dysarthria

Hypokinetic dysarthria (Hd), which often accompanies Parkinson´s Disease (PD), is characterized by hypernasality and by compromised phonation, prosody, and articulation. This paper proposes automated methods for detection of Hd. Whereas most such studies focus on measures of phonation, this paper focuses on prosody, specifically on fundamental frequency (F0) dynamics. Prosody in Hd is clinically described as involving monopitch, which has been confirmed in numerous studies reporting reduced within-utterance pitch variability. We show that a new measure of F0 dynamics, based on a superpositional pitch model that decomposes the F0 contour into a declining phrase curve and (generally, single-peaked) accent curves, performs more accurate Hd vs. Control classification than simpler versions of the model or than conventional variability statistics.