The role of predictability in shaping phonological patterns

A diverse set of empirical findings indicate that word predictability in context influences the fine-grained details of both speech production and comprehension. In particular, lower predictability relative to similar competitors tends to be associated with phonetic enhancement, while higher predictability is associated with phonetic reduction. We review evidence that these in-the-moment biases can shift the prototypical pronunciations of individual lexical items, and that over time, these shifts can promote larger-scale phonological changes such as phoneme mergers. We argue that predictability-associated enhancement and reduction effects are based on predictability at the level of meaning-bearing units (such as words) rather than at sublexical levels (such as segments) and present preliminary typological evidence in support of this view. Based on these arguments, we introduce a Bayesian framework that helps generate testable predictions about the type of enhancement and reduction patterns that are more probable in a given language.