Abstract:

Although cross-sectional (group) investigations of children's speech production have provided important findings about average performance and general patterns of development, one limitation of such studies is that they tend to obscure details concerning the development of individual children. In the present study, two children were recorded at approximately 8-month intervals for about 5 years as they produced 20 repetitions (per session) of several different target stimuli. One of the children was about 11/2 years old at the onset of the study, and the other was about 4 years of age. Acoustic measurements of various temporal aspects of their speech were obtained from spectrographic displays. The findings for both children showed certain patterns that supported the general claim (based on cross-sectional data) that segment and word duration and their associated temporal variability tend to decrease with increased age. However, there were also a number of instances in which the children's temporal variability and, in particular, their duration measures showed little or no change across the five years they were followed. Although the findings are from just two children, the implications of these longitudinal data are important for gaining a more detailed and comprehensive understanding of children's speech production development.