Acoustic analysis of prosody in females with Parkinson's disease: comparison with normal controls

Background: Voice abnormalities, collectively labeled as hypokinetic dysarthria, have been well characterized and occur in 90% of Parkinson's disease (PD) patients. However, studies of speech in PD, particularly of patients whose native language is other than English, are rarely found. The aim of this study is to compare the prosodic features of the speech of female PD patients and gender- and age-matched controls using acoustic analysis. Method: We have studied 8 PD female patients (68.4 +/- 6.4 years) and 8 female controls (63.5 +/- 6.8 years). The PD patients (H-Y stage 2, one subject; stage 2.5, four patients; stage 3, three patients), although treated with I-dopa, were examined when off. The fundamental frequency (Fo), intensity and duration of the speech were analysed with the software WinPitch 1.8 (Philippe Martin(R)). The analysed Fo parameters were: usual Fo (Fo us), maximal Fo (Fo max), minimal Fo (Fo min), Fo max of the prenuclear tonic (Fo max PNT), Fo min of the prenuclear tonic (Fo min PNT), Fo max of the nuclear tonic (Fo max NT), Fo min of the nucleartonic (Fo min TN), velocity of melodic variation of the PNT (VPNT), velocity of melodic variation of the NT (VNT), amplitude of melodic variation of the PNT (APNT), and amplitude of melodic variation of the NT (ANT). Duration of the statement (D), duration of the PNT (DPNT), duration of the NT (DNT) and number of sylables per second (NSS) were the duration parameters investigated. The following intensity variables were studied: mean intensity (MI), maximal intensity (I max), minimal intensity (I min), intensity of the PNT (IPNT) and intensity of the NT (INT). Differences were statistically significant if p<0.05. Results: PD patients had significantly lower Fo max (232.1 +/- 32.9 Hz), lower Fo max PNT (168.5 +/- 83.5 Hz), lower Fo max NT (182.1 +/- 29.5 Hz), lower VNT (0.2 +/- 0.1 Hz), smaller APNT (20.4 +/- 12.1 Hz), smallerANT (26 +/- 12.6 Hz), smaller NSS (4.8 +/- 0.1), higher IM (32.7 +/- 5.6 dB), higher I max (37.1 +/- 2.9 dB), higher I min (23.2 +/- 6.1 dB) and higher IPNT (35.4 +/- 2.9 dB) than controls (respectively: 248.7 +/- 23.9 Hz, 216.4 +/- 25.6 Hz, 197.5 +/- 35.8 Hz, 0.3 +/- 0.2 Hz, 22.7 +/- 15.9 Hz, 36.3 +/- 21.8 Hz, 5.3 +/- 0.8, 30.4 +/- 6.1 dB, 20.2 +/- 6.6 dB, 33.1 +/- 2.9 dB, and 30.9 +/- 4.3 dB. Conclusion: In comparison with controls, Brazilian female PD patients have a slower speech characterized by a narrow range of Fo variation (which likely accounts for the poor vocal tessiture of parkinsonian speech) and higher intensity. The latter is consistent with a compensatory attempt to overcome the latter.