Changing trajectories of New Zealand English vowels

It is well established that New Zealand English vowels have undergone considerable change over the last century and a half (Gordon et al., 2004). In this paper, we look at further change in the vowel system by exploring formant trajectories for both monophthongs and diphthongs in 310 speakers in the Quakebox Corpus (Walsh et al., 2013, recorded in 2010/11), born between 1920 and 1993. For most age cohorts, we find evidence of a continuation of changes that have already been documented. For example, when compared with data from earlier recordings (i.e., Hay and MacClagan, 2010), we see continued lowering of the second half of MOUTH, where F1 now generally increases over the course of the vowel, /æo/ → /ɛɐ/, even for the oldest speakers in our dataset. We also see evidence of further diphthongization of FLEECE, and LOT and THOUGHT are considerably higher when compared with speakers from the ONZE corpus (see Brand et al., 2021). But the most striking pattern is clear reversals in almost all vowel changes for the youngest groups of speakers, born between 1985 and 1993 in our data (ages 18–25 at the time of recording), supporting complementary findings by Ross et al. (2023, 2024).