Acoustic Characteristics of Speech of Patients with Parkinson’s disease in Greek

Presented at the 12th International Congress of Parkinson’s Disease and Movement Disorders, Chicago, IL, June 22–26 June 2008

Papathanasiou I,1 Protopapas A,2 Themistocleous M,3 Deligiorgi G,1 Lolakidou A,1 Kasselimis D,4 Boviatsis E,3 Stathis P,5 & Sakkas D3
1 Department of Speech & Language Therapy, TEI Patras Greece
2 Institute for Language & Speech Processing / Athena, Greece
3 Department of Neurosurgery, Medical School, University of Athens, Greece
4 Department of Psychology, University of Crete, Greece
4 IKA, Athens, Greece

Objective: To evaluate the acoustic characteristics such as fundamental frequency, jitter, shimmer, intensity, formants etc in the speech produced by patients with Parkinson’s disease (PD) in Greek, comparing with matched control group.

Background: Speech impairment is common among PD patients. Previous studies have shown that these speech difficulties are related only to phonation in 28% of the cases, or in combination with articulation, speech fluency and prosody. Regarding phonation this is characterized with reduced pitch due not only to reduction in fundamental frequency but also to reduced ability to alter fundamental frequency according to speech demands. Also the reduced intensity observed in PD patients is related to reduced respiratory support.

Method: We conducted a study to measure the acoustics characteristics of speech in six cases with PD in comparison with six age-, gender-, and education-matched controls. Data were collected in a variety of speech tasks, such as reading words, reading passages, narrative speech, and also simple phonation tasks such as sustained production of /a/. Measures of articulation, motor impairment, cognitive function and functional ability were collected with the Frenchay Dysarthria Test, Mini Mental Test, and UPDRS. Speech and voice samples were recorded to facilitate the analysis. Two trained speech & language therapists carried out the analyses.

Results: The results demonstrated significant differences in several speech and phonation related variables. From the articulation variables the observed differences were in the tongue movements and especially related to the production of the back sounds. This was confirmed with significant differences in the voice onset time for velar sounds and also in acoustic measures, mainly for the vowel /u/ (articulated in the back of the mouth). Differences were also observed in maximum phonation time for both voiceless and voiced sounds, indicating reduced respiratory support.

Conclusions: Our findings suggest that the nature of the speech impairment observed in patients with PD seems to be related to phonatory and articulatory variables of speech and reduced respiratory support. Our data are in agreement with previous reported studies in other languages.