Shifting dynamics in the closing diphthong system of New Zealand English
We present a dynamic acoustic analysis of over a century of changes in PRICE, MOUTH, FACE and GOAT in New Zealand English. We consider these diphthongs as parts of a system evolving as a coherent whole, and present a non-parametric analysis of full formant contours using generalised additive models. Our oldest speakers show an unremarkable system: PRICE/MOUTH start with low central nuclei, while FACE/GOAT start with mid front/back nuclei; both sets of vowels end in high offglides (front for PRICE/FACE and back for MOUTH/GOAT). This system undergoes dramatic restructuring over the course of 100 years. The final system consists of vowels that are all similar in height, but show (i) a broad distinction between centring diphthongs with lengthened nuclei (PRICE/MOUTH) and closing-fronting diphthongs (FACE/GOAT); (ii) different starting points but identical endpoints in PRICE and MOUTH; and (iii) FACE and GOAT distinguished mainly by a difference in frontness.
