Variability of formant values at different time points of vowels

Abstract

Vowel inherent spectral change research has led to two apparently contradictory conclusions about the appropriate representation of vowels: perception studies support a dual-target model of vowels, while production studies focus on calculating higher-fidelity continuous formant contours. This study explores production data in a new way by analyzing where in vowel duration variability is lowest across tokens. Portions of vowels that are less variable across tokens are assumed reflect greater importance to or planning by speakers. Born-and-raised Wisconsinites aged 18–30 were recorded reading a word-in-frame reading list eliciting 30 tokens of 14 American English vowels in the context /hVd/. F1 and F2 were sampled at 50 evenly spaced intervals for each vowel, covering the entire duration. For every speaker, the standard deviations of F1 and F2 were taken separately at every sample. Variability was analyzed as a function of time point. An upturned parabola pattern suggests a single target, a downturned parabola pattern suggests a dual target, and a horizontal pattern suggests continuous specification. For monophthongs, variability is found to be convex, and it is concave for diphthongs. This analysis does not support a dual-target model for monophthongs.