Michael Wagner will be giving a colloquium talk at University of Maryland on Friday, Sept. 13, 2019, titled “Allophonic variation and the locality of production planning”, reporting on joint work with Oriana Kilbourn-Ceron, James Tanner, Meghan Clayards, and Morgan Sonderegger. Here is the abstract:
The application of allophonic processes across word boundaries (so-called ‘sandhi’-processes, such as flapping (cf. De Jong, 1998; Patterson and Connine, 2001) and sibilant assimilation (cf. Holst and Nolan, 1995) in English, or liaison in French (Durand and Lyche, 2008)) is known to be subject to locality conditions. The same processes are also known to be variable. While these two properties have often been observed as characteristic of  sandhi (e.g. Kaisse, 1985), existing theories of either aspect do not explain the link between the two. This talk reports on a project that pursues the hypothesis that the locality and variability of cross-word allophonic processes are tightly linked, and can both be understood as a consequence of the locality of production planning.

The basic idea is that flapping, sibilant assimilation, liaison and related processes are sensitive to the phonological properties of a following word, but these can only exert their effect if they are already available when the phonetic detail of the current word is being planned. Under this view, effects of syntax and prosody on sandhi are due to their indirect effects on production planning. For example, a speaker is less likely to plan ahead across a sentence boundary. This hypothesis predicts that all factors affecting planning should affect the likelihood of cross-word allophonic processes (such as the predictability of the following word, the # syllables of the following word, etc.). The account makes novel predictions about what types of phonological processes, including certain kinds of phonologically-conditioned allomorphy, will necessarily have to be local and variable. It also makes different predictions than accounts of sandhi in terms of gestural overlap (Browman & Goldstein 1992), or accounts that try to rationalize sandhi phenomena directly based on predictability (Hall, Hume, Jaeger, & Wedel 2018).