A duration‐dependent account of coarticulation for hyper‐ and hypoarticulation. Free

Hyperarticulated and hypoarticulated speech are accompanied by spectral expansion and spectral reduction of vowel nuclei, respectively. These shifts in F1/F2 vowel space directly affect degree of anticipatory coarticulation in consonant + vowel sequences apart from traditional vowel context effects. Examining the opposite conditions of emphatic stress [Lindblom et al., J. Acoust. Soc. Am. 121, 3802–3813 (2007)] and faster speaking rates (Agwuele et al., Phonetica, in press) it was shown that coarticulatory effects could be documented independently of the expected vowel expansion/reduction effects. A modified locus equation regression metric was used in both studies to isolate alterations in F2 transition onsets due to prosodic and speech rate conditions apart from vowel space shifts per se. The current study provides a unified empirical and theoretical account for the opposite coarticulatory effects by providing duration data as the common variable tying both studies together. Articulatory and acoustic simulations of deeper (emphasis) and shallower (increased tempo) closures are provided to explain the shifts of observed F2 onsets relative to predicted F2 onsets due simply to expanded/reduced vowel space.