Contour tones in Igbo: 'Where they come from'

Abstract

Contour tones are typically predominant in tone languages operating a contour system in contrast with tone languages operating the register system. This paper examines the underlying and surface characterization of contour tones (rising and falling tones) at the lexical level in Igbo. Adopting the Autosegmental approach originally proposed by Goldsmith (1976), it reinforces the composite nature of both contours in Igbo. From the data, evidence is given that contour tones in Igbo are mere surface features which are motivated by some underlying rules that arise from the merging of tone at morpheme boundaries, historical loss of segments and the association of a floating tone. The two rules are identified are the deletion and docking rule. The manifestation of the latter is premised on the application of the former. The application of both rules is equally dependent on the fulfilment of some tone contour conditions such as presence of morpheme boundary, occurrence of contrasting tones at the morpheme boundary, similarity of vowels. The data used for this study are mostly individual words (place names and general nouns). These nouns are however morphologically derived complex words. The analysis shows that contour tones are usually induced at morpheme boundaries. Again, there is always a collapse of the contrasting tones realised on the tone bearing units (vowels) at the morpheme boundary. The morpheme boundary as used in this context and as applicable to Igbo is restricted to free morphemes. The first morpheme whose vowel is always affected by the deletion rule could start losing its original meaning overtime. © 2014 Academy Publisher Manufactured In Finland.