Grounded constraints and the consonants of Setswana

The article examines the phonology and phonetics of Setswana obstruents and the well known and controversial post-nasal devoicing rule, which has been cited as a counterexample to the claim that markedness constraints are phonetically grounded (Hyman, 2001). We re-examine the case of Setswana and argue that it must be analyzed in terms of grounded constraints. Our evidence comes from two sources. First, we report on the results of a phonetic study of six speakers of the Sengwato dialect of Setswana. We found that some of our speakers did not have voiced obstruents in any context. Those speakers that did devoice post-nasally also devoiced in other contexts. Thus, a phonetic examination of the purported counterexample to phonetically grounded constraints fails to support the traditional descriptions. Second, we examine the larger phonological context in which the Setswana alternations occur. Setswana has a gapped system of laryngeal contrasts, so the evidence for post-nasal devoicing comes almost entirely from labial stops. The language also has a series of so-called strengthening alternations that affect consonants such as liquids and fricatives post-nasally-alternations that we propose to analyze in terms of the Syllable Contact Law.