Acoustic characteristics of Parkinsonian speech: A potential biomarker of early disease progression and treatment

Date of Completion

January 2004

Keywords

Health Sciences, Medicine and Surgery|Psychology, Physiological

Degree

Ph.D.

Abstract

Nearly two centuries ago, James Parkinson (1817) first observed that a particular pattern of speech changes occur in patients with idiopathic Parkinson's disease (PD). Numerous studies have documented these changes using a wide variety of acoustic measures, and yet few studies have attempted to quantify any such changes longitudinally, throughout the early course of the disease. Moreover, we were unable to identify any attempt made to examine the effects of initiating pharmacologic intervention on acoustic measures. This two-experiment study is an attempt to determine if certain acoustic measures (e.g., fundamental frequency [F0] variability in free speech, VOT, and pause duration) are sensitive to early pathophysiologic changes in the course of the disease as well as to the initiation of pharmacologic treatment. In the first experiment, a retrospective analysis of videotape footage obtained from a leading national television news service was conducted on two well-known individuals with PD (and two well-matched controls) over approximately a 10-year period surrounding the time of diagnosis. A decrease in F0 variability during free speech was detected prior to clinical diagnosis. In addition, changes in F0 variability and VOT were detected upon initiating symptomatic treatment. ^ The second experiment served to provide evidence of convergent validity for the initial experiment, and to determine whether any observed changes in PD patients were different from matched healthy controls. A cross-sectional analysis was conducted on four newly diagnosed PD patients and four controls using a standard protocol for acquiring voice acoustic measures. F0 variability during free speech was found to be diminished relative to matched controls at approximately the time of diagnosis. In addition, pause duration was greater in PD patients relative to matched controls. However, no changes in voice onset time (VOT) were detected. The results of both experiments suggest that pathophysiologic changes early in the course of the disease are detectable using certain voice acoustic measures. In particular, F0 variability appears to be sensitive to early changes in the course of disease and to the initiation of pharmacologic intervention even under less than ideal voice recordings conditions. ^

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