CONTOUR AS TOMORPH IN ÍSÓKÓ: AN AUTOSEGMENTAL APPROACH

Abstract

This paper investigates the presence and grammatical significance of a rising tone morpheme—termed tomorph—in the Ísókó language, an Edoid language spoken in parts of Delta and Bayelsa States, Nigeria. Drawing from the theoretical framework of Autosegmental Phonology, the study argues that the rising tone, though segmentless at the underlying level, functions as a morpheme marking negation in sentence-final positions. Through detailed phonological analysis and empirical data, the research demonstrates that this floating tone associates with tone-bearing units (TBUs) via autosegmental principles such as mapping, dumping, delinking, and spreading. The study provides compelling evidence that suprasegmental features such as tone can carry morphosyntactic information, supporting the view that tone and segment reside on distinct autonomous tiers. This work contributes to the growing literature on tonal morphology in African languages and highlights the need to further explore the grammatical role of contour tones.