Advancement of phonetics in the 21st century: Exemplar models of speech production

In the first decades of the 21st century, exemplar theory has fueled an explosion of theoretical and empirical work in speech production. We review the foundations for this framework in linguistics and cognitive science, and examine how recent empirical findings challenge core principles of exemplar theory. While theoretical advances in hybrid exemplar models address some of these issues, accounting for the emergence of structure, the incorporation of structure into exemplar updating, and the non-uniformity of phonetic variation and convergence (among other phenomena), remain major challenges for current models. We discuss future directions for developing exemplar theories as comprehensive accounts of speech production.