Abstract:

To follow up on an earlier, 11/2-yr longitudinal study of temporal characteristics in speech production development [Smith et al., J. Acoust. Soc. Am. 99, 2344--2349 (1996)], the same 12 children were seen again to extend the analysis interval to about 3 yr. The children ranged from approximately 7--12 years of age initially to about 10--15 years at the end of the study. For each recording, they produced 25 repetitions of each of several different words and short phrases, from which various segments and syllables were measured. Duration and temporal variability measures for up to half the subjects demonstrated nonadultlike performance at the initial and intermediate recordings, whereas average duration and variability were within an adultlike range for all 12 children by the final session. In general, the greatest decreases across the 3 yr occurred during the first 11/2 yr, particularly regarding temporal variability; however, small decreases in duration and variability occurred from the intermediate to the final recording, as well. A tendency was also observed for children whose average segment duration or variability was more adultlike at the initial recording to show more adultlike values at the intermediate and final recordings.