A longitudinal investigation of formant frequency development in childrens’ speech production

Abstract

While cross-sectional/group investigations provide important findings about the development of speech production, such studies do not furnish details regarding the development of individual children across time. However, such information is necessary for understanding childrens’ speech production development more thoroughly and for evaluating, from a somewhat different perspective, ideas that have been proposed on the basis of cross-sectional findings. In the present study, four subjects were recorded at approximately one-year intervals for four to six years as they produced about 20 repetitions (per session) of each of several target stimuli; three of the children were approximately 11/2 years old at the onset of the study, and the other was about 4 years of age. Measurements of F1 and F2 for three different vowels for all four children showed some patterns supporting the general notion that formant frequencies tend to decrease with increased age. However, there were also a number of instances in which a particular child’s formant frequency values showed little or no change across the entire 4–6 years. These longitudinal data suggest that childrens’ formant frequency values do not necessarily decrease in a consistent fashion with increases in age and physical size.