Studying vocal fold vibrations in Parkinson's disease with a nonlinear model.
A nonlinear model is applied to study pathologic vocal vibratory characteristics and voice treatments of Parkinson's disease. We find that a number of pathologic vocal characteristics commonly observed in Parkinson's disease, including reduced vibratory intensity, incomplete vocal closure, increased phonation threshold pressure, glottal tremor, subharmonics, and chaotic vocal fold vibrations, can be studied with this nonlinear model. We also find that two kinds of clinical voice treatments for Parkinson's disease, including respiratory effort treatment and Lee Silverman voice treatment can be studied with this computer model. Results suggest that respiratory effort treatment, in which subglottal pressure is increased, might aid in enhancing vibratory intensity, improving glottal closure, and avoiding vibratory irregularity. However, the Lee Silverman voice treatment, in which both subglottal pressure and vocal fold adduction are increased, might be better than respiratory effort treatment. Increasing vocal fold thickness would be further helpful to improve these pathologic characteristics. The model studies show consistencies with clinical observations. Computer models may be of value in understanding the dynamic mechanism of disordered voices and studying voice treatment effects in Parkinson's disease.
Zhang
Yu
Y
Department of Surgery, Division of Otolaryngology Head and Neck Surgery, University of Wisconsin Medical School, Madison, Wisconsin 53792-7375, USA.
Jiang
Jack
J
Rahn
Douglas A
DA
D003198:Computer Simulation; D006801:Humans; D008954:Models, Biological; D017711:Nonlinear Dynamics; D010300:Parkinson Disease / Q000150:complications / Q000503:physiopathology*; D013064:Speech Disorders / Q000209:etiology / Q000503:physiopathology / Q000628:therapy; D013068:Speech Production Measurement / Q000379:methods; D013070:Speech Therapy / Q000379:methods; D013813:Therapy, Computer-Assisted / Q000379:methods; D016896:Treatment Outcome; D014732:Vibration; D014826:Vocal Cord Paralysis / Q000209:etiology / Q000503:physiopathology* / Q000628:therapy*; D014827:Vocal Cords / Q000503:physiopathology*; D014832:Voice Disorders / Q000209:etiology / Q000503:physiopathology* / Q000628:therapy*; D014834:Voice Training