Developmental use of vowel duration in perception and production

Abstract

This study was designed to investigate developmental use of vowel duration as a cue to postvocalic consonant voicing in both perception and production. The subject sample consisted of 10 three-year-olds, ten six-year-olds, and ten adults, with normal articulation and language skills and normal hearing sensitivity. For the perception study, steady-state vowel duration was varied in each of the three synthetic continua BIP-BIB, POT-POD, BACK-BAG. The percentage of responses judged as voiced was calculated by subject for each synthetic stimulus value and plotted against vowel duration, yielding 90 sets of identification data. The logistic function was fit to these data by maximum likelihood techniques. Two parameters, crossover and slope, were obtained from each fitted function and served as dependent measures for statistical analyses. For the production study, total vowel duration was measured in ten trials of each of the six test words, BIP, BIB, POT, POD, BACK, and BAG, for each speaker. Comparative analyses between the perception and production data revealed a refinement in the use of vowel duration, with an increase in age.