Understanding lenition through its causal structure
Uriel Cohen Priva, Brown University
Consonant lenition refers to a list of seemingly unrelated processes that are grouped together by their tendency to occur in similar environments (e.g. intervocalically), and under similar conditions (e.g. in faster speech). These processes typically include degemination, voicing, spirantization, approximantization, tapping, debuccalization, and deletion (Hock 1986). What is common to all these processes? Why do they happen? Different theories attribute lenition to assimilation (Smith 2008), effort-reduction (Kirchner 1998), phonetic undershoot (Bauer 2008), prosodic smoothing Katz (2016), and low informativity (Cohen Priva 2017). We argue that it is worthwhile to focus on variable lenition (pre-phonologized processes), and on two phonetic characteristic of lenition: reduced duration and increased intensity. Using mediation analysis, we find causal asymmetries between the two, with reduced duration causally preceding increased intensity. These results are surprising, because increased intensity (increased sonority) is often regarded as the defining property to lenition. The results simplify the assumptions associated with effort-reduction, prosodic smoothing, and low informativity, and are compatible with phonetic undershoot accounts.