A diachronic perspective on interspeaker covariation in sound change

Philadelphia English has been undergoing multiple vowel changes throughout the twentieth century. Using data from the Philadelphia Neighborhood Corpus (PNC), Labov et al. (2013) demonstrate that some of these changes reversed direction mid-century while others continued in a single direction. In Tamminga (2019), I show that among today’s young women, there is significant interspeaker covariation between reversing changes but not continuing ones. This talk extends this analysis to the full timespan of the PNC data for five vowels. I find that the correlations between the reversing changes are present in the community prior to the overall reversal peaks, suggesting that covariation may drive, rather than reflect, long-term change trajectories. I further discuss the place of the continuing changes in the covariation picture and broader theoretical implications.