Voice onset time in normal-aged population

Evidence suggests that the fine motor coordinations required to maintain the articulatory-laryngeal adjustments represented by measures of voice onset time (VOT) should change as a function of normal aging. This descriptive study obtained measures of VOT in healthy elderly subjects as a basis for extending the model of temporal speech control to the later years. Three groups of 10 subjects each were used. Group I was composed of subjects 25-39 years old. Groups 2 and 3 included subjects aged 65-74, and over 75, respectively. Subjects produced 30 tokens of three stimulus words, beat, pete, bead, following a carrier phrase. Wide-band spectrograms were prepared and measured, and the VOT data analyzed statistically. The following conclusions were drawn with respect to mean group age. The means of the VOTs did not differ significantly across subject groups. Standard deviations in the means did differ significantly, variability increased with age, both within subjects and between groups. The minimal separation of the phonemic boundaries for /b/ and /p/ decreased significantly as a function of aging, with the /p/ side of the distribution showing the greatest change.