Effects of experimental manipulations and intrinsic contrasts on relationships between duration and temporal variability in children’s and adults’ speech

Abstract

To assess two competing hypotheses pertaining to children’s speech production development, relationships between segmental durations and their associated variability (as measured by standard deviation) were studied in three groups of children and a group of adults who produced a variety of stimuli under normal, fast rate and bite block conditions. Because it was found that there were very few significant correlations between duration and variability, it was concluded that these two parameters do not manifest merely a mathematical relationship, as has sometimes been suggested. Findings based on the rate change data, as well as comparisons of duration and standard deviation for intrinsically short vs. long segments, also indicated that duration and variability are not very closely correlated. The fact that duration was found to approach adult-like levels at a younger age than variability provided additional support for the conclusion that duration and variability are relatively independent measures that can both be used for gaining a better understanding of children’s speech production development.