Positional Prominence and the “Prosodic Trough” in Yaka

The issue of Bantu vowel height harmony is one that most serious theories of phonology have addressed at one time or another. As is quite well-known, the majority of an estimated 500± Bantu languages exhibit some variant of a progressive harmony process by which vowels lower when preceded by an appropriate (lower) trigger. In this paper I have three goals. First, I present a comprehensive treatment of the unusual vowel harmony system in (ki-)Yaka, a Western Bantu language spoken in ex-Zaire, designated as H.31 by Guthrie (1967-1971). Second, I introduce the notion of the prosodic trough (τ), a domain which is needed in order to state important phonological generalizations in Yaka and in Bantu in general. Finally, I show the relevance of the Yaka facts for the study of positional prominence in phonology. A (partial) analysis is offered within optimalitytheoretic terms, particularly as developed by McCarthy & Prince (1995). Although superficially resembling the vowel height harmony found in most Bantu languages, the Yaka system will be shown to differ from these latter in major ways. The paper is organized as follows. In §2 I establish the general nature of the Yaka harmony system, reanalyzing previous accounts in terms of “plateauing”. In §3 I turn to the process of “imbrication” which introduces a second motivation for vowel harmony: the avoidance of the sequence [wi]. A third source of vowel harmony is presented in §4 which also introduces the notion of the “prosodic trough”. The study ends with a brief conclusion in §5 and an Appendix that discusses outstanding problems.1