An autosegmental approach to phonological phenomena in Shilluk.

Shilluk is a Western Nilotic language spoken in southern Sudan. Previous works on this language have failed to adequately capture the phonological and morphological systems of the language. An Autosegmental approach employed within a framework based upon the tenets of Lexical Phonology, allows the various aspects of Shilluk phonology to be separated in an insightful way. Thus, the vowel and consonant harmony systems, the tonal system, and the syllable structure may be dealt with independently. The thesis comprises six chapters: 1, Introduction, 2. Phonetics and Phonology, 3. The Representation of Lexical Items, 4. Syllable Structure, 5. Lexical Levels of Derivation, and 6. Summary. Chapter 2 provides a relatively 'autonomous' account of the consonants, vowels (including length), and tone. Chapter 3 presents evidence for the claim that it is necessary to set up independent underlying representations for the stems of singular and plural nouns, as well as for Transitive verb forms. Issues covered in this chapter are tone and the harmony systems - vowel harmony, vowel and consonant harmony, and consonant harmony. Chapter Four completes the argument for independent representations with a discussion of syllable structure. This chapter shows how syllable structure constraints may be invoked to account for surface vowel length alternations. In turn, this chapter adds another argument for the claim that most lexical items require dual (independent) underlying representations. The material in this chapter demonstrates that processes motivated by syllable structure make it the most influential factor in Shilluk phonology. In Chapter 5, the discussion turns to the ordering of levels within the Lexicon. By combining all the tone and syllable structure rules, it is possible to establish the presence of three levels within the Lexicon. A summary of all the rules developed in the thesis are given in the sixth chapter along with comments on the implications of this study with regard to language acquisition. Some suggestions are also made for further study