Phonetic duration is more variable than phonological duration

Duration may be phonologically meaningful, as with contrastive segment length or as a cue to stress, or it can be purely phonetic, as with final lengthening. This paper explores the amount of durational variation present in the articulation of rimes that have different sources of duration. We show evidence to support the hypothesis that phonological duration is more stable and phonetic duration is more variable. We present evidence from new analyses of two English production studies (Lunden 2016, 2017) with nonce words that show significantly greater durational variability due to final lengthening than durational differences due to vowel quality or stress. Variability in duration was calculated by looking at the residuals from Generalized Linear Models of raw duration. Subsequent homogeneity of variance tests (Levene's tests) were performed as part of one-way ANOVAs on the saved residuals as the dependent variable. We suggest that the greater variability of phonetic duration is plausibly responsible for weakening effects such as the avoidance of stress and avoidance of long vowels and geminates word-finally, as it is perceptually difficult to signal duration-based phonology in a position with highly-variable duration.