ABSTRACT
This chapter investigates the internal structure of the segmental melody in multitiered phonology. It argues for tier separation and dependent tier ordering, with the overall goal of maximizing the explanatory role of the Obligatory Contour Principle (OCP). The OCP requires that morphemes with several labials be represented with a single feature. The OCP requires that morphemes containing more than one coronal plosive on the surface be underlyingly represented with a single occurrence of the feature. Dependent tier ordering, together with the OCP, can explain the rather complex restrictions on root vowel cooccurrences found in Ngbaka, a language of the Eastern branch of the Congo-Kordofanian family. The basic idea is all restrictions are due to OCP conflicts on the height tier. The OCP-based explanation for the restrictions on the vocalism of Ngbaka morphemes presupposes the segregation of consonant and vowel features onto different tiers.
