The Effect of Levodopa on Vowel Articulation in Parkinson's Disease:A Cross-Linguistic Study

Parkinson's disease (PD) is a neurological disorderthat is characterized by a decay in global motorperformance, manifest in tremor, abnormal gait, anddysarthria. PD dysarthria characteristics includemonoloudness, pathological voice quality, andimprecise articulation. Standard treatment forrelieving PD symptoms is the drug Levodopa, but itis currently unknown how it affects speech. Weinvestigated the effect of Levodopa on the vowelspace of 4 Dutch and 6 Slovenian PD participants.They recorded their speech on twenty occasionsdistributed over four days across 2-4 weeks. First andsecond formants of corner vowels [i-a-u] produced inisolated words were measured at acoustic midpointsof 4043 tokens. VAI [13], a metric of vowel spacedispersion, was calculated for each speaker. VAI wasnot significantly affected by Levodopa in eitherlanguage, which may indicate that the motor controlunderlying vowel articulation is not as sensitive toLevodopa as other motor symptom