Voice onset time in Parkinson disease

Research has found that speaking rate has an effect on voice onset time (VOT). Given that Parkinson disease (PD) affects speaking rate, the purpose of this study was to examine VOT with the effect of rate removed (VOT ratio), along with the traditional VOT measure, in individuals with PD. VOT and VOT ratio were examined in 9 individuals with PD (before and after taking medication), along with 9 matched controls. Place of articulation and vowel height had significant effects on VOT and VOT ratio for all groups, and there were no PD versus control differences. PD medication had a greater effect on VOT than VOT ratio, reflecting a rate-related VOT change rather than a pure VOT change. These data support the usefulness of examining both VOT and VOT ratio with individuals with PD, as this allows for dissociation between rate-related VOT changes and true VOT changes.Learning outcomes: The reader will be able to understand and describe: (1) voice onset time (VOT) and VOT ratio; (2) how VOT and VOT ratio are affected in individuals with Parkinson disease; and (3) the effect of medication on VOT and VOT ratio.