Analysis Of The Acoustic Characteristics Of Chinese Patients With Parkinson's Disease

With the advent of rapid-aging phase of China, the life and disease needs more attention from the society. Parkinson's Disease (PD) is one of the degenerative diseases of the central nervous system in the middle and aged people attributing to dozens of factors. The dearth of study of Chinese PD speech makes it necessary to find auxiliary diagnosis in early disease stage and speech therapy in late from the aspect of speech.In order to gain the features of PD speech and the effect of medicine L-dopa on speech production, we conducted this research by recording and analysing the speech samples from PDs (on and off state) and matched healthy controls (HC) on the prosodic and articulatory features.The main contents of this research were listed as fllowing:(1) Is there any improvement of PD speech after taking L-dopa medication comparing with no medication?(2) What the differences of prosodic and articulatory features between PD and HC?This paper explored the changes of PD speech before and after the usage of L-dopa, and the prosodic and articulatoory differences of speech between PD and HC by behavioral experiment and acoustic analysis. Conclusions were displayed following.The first is the prosodic features, which were divided into two parts: the fundamental frequency (F0) and the duration.(1) In the aspect of the fundamental frequency, acoustic analysis showed that the FO variation of PD speech is small which contributed to the monotone. This seemed to illustrate that the impairment of vocal folds which was the result of rigidity muscules leaded to the difficulty in coordinating the vibration of vocal folds.(2) As for duration, PD's speech exhibits significantly faster rates (both speech rate and articulation rate), shorter vowel duration, and shorter voice onset time (VOT)than HC's. The deviation of VOT from normal indicates an imprecise inter-articulator timing coordination.The second is articulatory features, which were consisted of consants and vowels.(1) PD's speech introduces more frication in stops. This is evidenced by the significantly higher 'normalized minimum intensity'of stops than in HC's speech,as a result of air escape due to an incomplete obstruction. This occurs less in the bilabials"b,p" than in "d,t,g",suggesting that orbicularis oris controlling the lips is less impaired than those muscles controlling the tongue.(2) Vowel Articulation Indice is smaller in PD than HC, especially for female PD.This suggests that vowels in PD's speech are more centralized, which contributes to the lower intelligibility of PD's speech.In addition, there was little effect of L-dopa on speech except for a slight increase in mean FO even though not significantly.At the same time, correlation analysis based on acoustic parameters and physiological/pathological indexes showed that there was only a significantly negative corelation between FO range and age of PD,suggesting that PD accelerates the aging process.