Perceptual tolerance and phonetic re-analysis during a sound change in progress

How does a community of speakers advance a sound change without being consciously aware that a change is underway? This dissertation proposes one account, sociophonetic tolerance, and subjects four models to empirical testing on the Canadian Shift (CS). Sociophonetic tolerance views the listener as complicit in change via perceptual re-analysis of the phonetic categories undergoing change and considers variation in tolerance to be linked with the range of phonetic variation found in production. Results, based on categorization tasks involving 37 English-monolingual Ontarians, both contradict and support the model. The first experiment tasks, which looked at categorization of words containing variants of the vowels /I/ and /epsilon/ revealed no significant patterns of re-analysis in the direction of the shift. However, a second experiment task involving categorization of /ae/, shows significant patterns of re-analysis via perceptual extension: apparent-time data reveal that females and younger listeners exhibited a more centralized /ae/-/a/ boundary. This model of phonetic tolerance is motivated by studies which reveal variation in phonetic expectations in experimental tasks due to differences in linguistic experience and offers an account for how phonetic change from below might proceed through a speech community.