The present study investigated the effect of deep brain stimulation (DBS) of the subthalamic nucleus (STN) and the caudal zona inserta (cZi) on motor control and coordination in plosives. A total of 2520 plosive productions, recorded during production of alternate motion rate and sequential motion rate tasks, were measured for voice onset time (VOT) when measurement was possible. Failed measurements were classified by the underlying cause. The resulting data were analyzed separately for each place of articulation of the intended plosive and compared with the articulatory properties of plosives not meeting the requirements for VOT measurement. The results showed no consistent overall stimulation effect in VOT regardless of place of articulatory closure. Furthermore, no overall pattern concerning the distribution of factors causing failures to measure VOT was observed. Instead, the results suggest a more complex interaction among place of articulation, speech task, and stimulation target in the determination of treatment effects of DBS in patients with Parkinson's disease (PD). The results further suggest that VOT may not provide a robust estimate of treatment effects in articulatory proficiency related to plosive production in patients with PD.