| Summary: |
This thesis presents an autosegmental analysis of the tonal phonology of Yoruba. It utilizes a fully specified matrix of Yoruba tone features by contrast with recent 'underspecified-autosegmental' accounts. My contention is that, in the bid to apply tonal underspecification theory to Yoruba, my predecessors have not provided a proper account of certain processes. The work is laid out in eight chapters. Chapter One gives a general overview of the whole work. Chapter Two provides a brief introduction to Yoruba and highlights the controversial and non-controversial aspects of its tonology. The claims of autosegmental phonology and its application and relevance to Yoruba are discussed in Chapter Three. Chapters Four and Five deal with explanations of tonal processes within lexical items and across word boundaries respectively. Processes of linking, delinking, relinking, spreading, and freeing involving High, Mid and Low tones provide evidence that, whatever the diachronic facts of the Mid tone, Yoruba is still better analysed synchronically as having an underlying three-term tonal contrast. Claims relating to the hierarchical representation of tone features and the theory of tonal underspecification and proposals for the representation of multiple tone heights are examined in Chapter Six. It is also suggested that the Yoruba Mid tone is not to be seen exclusively as involving a split in either the lower or the higher register; and the analysis of the Yoruba mid tone as null or zero is challenged on the basis of the data discussed in Chapters Four and Five. I propose that, though certain instances of Yoruba mid tone may be analysed as being derived, not all cases can be explained in this manner. Finally, I propose further that a "base three" tone feature system rather than a "base two" system be adapted to suit Yoruba. Chapter Seven examines tone deletion both in the underspecified-autosegmental model and in the present analysis. It is pointed out that the analysis of tone deletion within the underspecified-autosegmental model has a number of problems, and that it is preferable to distinguish "tone deletion proper" from cases of tone lowering and tone raising. Chapter Eight, which examines a number of residual problems relating to polarity in a three-term tone system such as that of Yoruba, concludes the thesis.
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