Voice Onset Time in Healthy Young and Old Adults

Objectives: This study aimed to investigate age related changes in articulatory control by examining whether there were differences between young and elderly adults in their voice onset time (VOT). Methods: 16 adults over the age of 65 and 16 adults aged between 18-39 years old participated in this study. The experimental task consisted of 9 plosives, categorized by place of articulation and phonation type, paired with the vowel /a/ to form 2 syllable VCV non-words. Participants’ voice samples were analyzed using Praat. VOT mean was used to examine group differences in VOT and coefficient of variation (CoV) was used to examine group differences in VOT variability. Results: There were significant differences in VOT mean according to age group, phonation type, and place of articulation. The elderly adults had a longer VOT compared to the young adults with significant differences for place of articulation in velar plosives and significant differences for phonation type in aspirated plosives. There were significant differences in VOT CoV according to age group and phonation type. The elderly adults had higher VOT and CoV compared to the young adults with a significant difference in lenis plosives. Conclusion: The results of this study show that elderly adults have longer VOT durations and irregular articulatory control, reflected by higher VOT variability, compared to younger adults. These results may reflect age related declines in the coordination of the speech mechanism and reduced oral motor control.