A developmental study of vowels spoken in syllables and in sentence context

Abstract

This study examined the effects of context on the production of vowels spoken by children of different ages in isolation and in a carrier sentence. Vowels were extracted from a database of hVd syllables produced by 207 native English talkers from the North Texas region, ranging in age from 5 to 18 years with approximately equal numbers of males and females. Preliminary analysis of a subset of the database (around 25% of talkers) showed a systematic reduction in vowel duration with increasing age for syllables in isolation. Vowels in sentence context were on average 30% shorter than in isolated syllables, and durations were less closely linked to age group. Formant frequencies (F1–F3) showed similar patterns for vowels in isolated syllables and sentences, and decreased as a function of age as expected. However, measures of formant movement across the vowel (from 20 to 80% of the vowel duration) revealed increased F1 and F2 movement for syllables in isolation compared to those produced in carrier sentences. A comprehensive analysis of the database will be presented and implications for vowel recognition will be discussed.