Study of voice disorder based on acoustic assessment in Parkinson ′s disease

Objective To analyze the acoustic features of patients with Parkinson′s disease (PD), and to explore the correlation between the acoustic features and the severity and course of disease. Methods Fifty-two patients with PD from the Tongji Hospital Affiliated to Tongji Medical University and the Ninth People′s Hospital Affiliated to the Medical College of Shanghai Jiaotong University from August to December 2015 were enrolled into this study. Thirty-two age-matched healthy people served as control group. PD patients were tested with Unified Parkinson′s Disease Rating Scale (UPDRS) and Hoehn-Yahr (H-Y) staging. And all the patients were tested with Mini-Mental State Examiantion (MMSE) and Voice Handicap Index (VHI). The voice samples of all subjects were collected and the frequency perturbation (jitter), amplitude perturbation (shimmer), and harmonic-to-noise ratio (NHR) were analyzed using a vocal assessment. Fundamental frequency (F0), standard deviation of fundamental frequency (SDF0) and formant ratio (F2i/F2u) were analyzed using a real-time speech measuring instrument. The acoustic parameters of the two groups were compared and the correlation between the parameters of the patients and the disease and course of disease was analyzed. Results Subjective assessment using VHI showed a total of 24 VHI abnormalities (46%) in the PD group, including 13 males (54%), 11 females (46%). No VHI abnormalities were found in the control group. Among the parameters analyzed by objective acoustic method, compared with the control group (female/a/1.43(1.19, 1.92),/i/3.39(1.49,9.85),/u/1.46(1.23,3.85); male/a/1.06 (0.92, 1.89) ,/u/1.30(1.07,1.64)), the SDF0 of the three vowels of the female patients in the PD group (/a/2.99(1.81, 4.12), Z=5.429, P<0.01; /i/10.89(5.47, 22.20), Z=8.487, P<0.01; /u/5.16(3.75, 7.80), Z=7.138, P<0.01) and /a/and/u/of the male patients in the PD group (/a/2.16 (1.73, 2.94) , Z=4.858, P=0.002; /u/3.70(2.41, 5.43), Z=7.664, P<0.01) were significantly increased, and the F2i/F2u in the PD group (male 1.96±0.84, female 1.81±1.14) was lower than that in the control group (male 3.48±0.70, female 4.14±1.08), and the difference was statistically significant (t=-6.669,-6.844, P<0.01). There were no statistically significant differences in frequency perturbation, amplitude perturbation, harmonic noise ratio and fundamental frequency. Only the fundamental frequency standard deviation of the sound parameters used in the study was correlated with the disease course of PD patients. After the severity of the disease was assessed by H-Y staging, the frequency perturbation (jitter), amplitude perturbation (shimmer) in the middle and late stage patients were higher than those in the early stage patients, and the difference of frequency perturbation in the three vowels was statistically significant, and the difference of amplitude perturbation in the vowels/i/and/u/was statistically significant. No correlation was found between the acoustic parameters and UPDRS score. Conclusions Consonance disorders are common in PD patients, and the changes in acoustic parameters are mainly manifested as the increase in the SDF0 and the decrease in the F2i/F2u. Acoustic parameters can be used as an effective indicator to evaluate the condition and course of PD patients, and further language tasks need to be added to clarify. Key words: Parkinson disease; Articulation disorders; Speech acoustics