Sheard, Elena2023-05-232023-05-23http://hdl.handle.net/1885/292110The field of lifespan change - which studies the speech of the same individuals over time - has identified three main trajectories that speakers follow: participating in wider community change ('lifespan change'), not participating (stability), and moving in the opposite direction to the community ('retrograde change') (cf., Sankoff 2019). When individuals do change, there is also great variability, as people do not change the same amount over the same period. There is, however, limited systematic analysis of why this is the case. In my thesis I investigate whether it is possible to systematically explain a) the trajectories individual speakers have followed, and b) the extent to which they have changed. I apply this question to a set of variables in Australian English, including diphthongs, monophthongs, word-final (er), and (ing). The investigation is based on a panel study of five Greek- and five Italian- background Australians, who were recorded in the 1970s as teenagers for the Sydney Social Dialect Survey (Horvath 1985) and again in 2019 as adults for the Sydney Speaks project (Travis, Grama, and Gonzalez In Progress). Through contextualising the speech of these 10 individuals within the broader patterning of their generation (an additional 117 Australians from the Sydney Speaks corpus) using innovative quantitative methodologies, I can answer in the affirmative to the two research questions: the individuals who change most are those who were originally further behind in the change relative to their peers. This pattern is displayed across the set of studied variables and holds for individual speakers; individuals consistently move more over their lifetime for variables in which they are lagging in the change. However, individuals are not consistently progressed across the variables; an individual being ahead in one change cannot be reliably used as proxy for being progressed in another. This thesis supports the importance of the speech community in accounting for trajectories over the lifespan. It also highlights the potentially underestimated role of speakers' own generation in providing targets for change over the lifespan, and problematises the distinction between retrograde and lifespan change in situations where different speakers converge on a shared target from different starting points in their youth.en-AU202310.25911/0E9J-EQ77