The phonetics and phonology of the Lopit language

Abstract

This thesis is an investigation of the sound system of Lopit, an Eastern Nilotic (Nilo-Saharan) language traditionally spoken in South Sudan. The primary aim of this study is to develop a phonetically-based description of aspects of Lopit segmental and tonal phonology, with a focus on the Dorik variety of the language.

This is first approached via analyses of phonological and morphological patterns in Lopit, using data collected during extended fieldwork with members of the Lopit community in Melbourne, Australia. A number of hypotheses regarding Lopit phonological contrasts and processes are put forward, including proposals for nine monophthongs, an inventory of 27 consonants, and three tones used for both lexical and grammatical distinctions. Some differences in the number and nature of contrasts are found compared to observations in the limited existing materials on Lopit.

Four production experiments are then undertaken to examine the acoustic and articulatory evidence for three phenomena of particular interest. The first is the phonological feature ‘Advanced Tongue Root’, widely attested in African languages and here suggested to distinguish monophthongs /i, e, o, u/, labelled [+ATR], from /ɪ, ɛ, a, ɔ, ʊ/, labelled [-ATR]. The results of an acoustic experiment reveal lower first formant frequencies as the primary correlate distinguishing [+ATR] from [-ATR] vowels, and a following ultrasound-based experiment shows that vowels in the [+ATR] set have a more anterior tongue root position than those in the [-ATR] set.

Length contrasts proposed for selected obstruents and sonorants include a contrast between singleton glides /w, j/ and geminate glides /wː, jː/, a typologically uncommon distinction which has received little phonetic attention crosslinguistically. The results of an acoustic investigation of Lopit glides show that duration is a robust correlate of glide contrasts at the same place of articulation, with the putative geminates being significantly longer. Furthermore, they have a more constricted articulation, as evidenced by lower first formant frequencies and lower root-mean square amplitude values.

An acoustic experiment testing the proposed contrast between High, Low and Falling tones confirms that these three tones are distinct, with higher fundamental frequency values for the High compared to Low tone, and a trajectory of high to low values for the Falling tone. It is also shown that the fundamental frequency and duration characteristics of these tones are sensitive to the tonal context in which they occur.

These experiments contribute the first phonetic data on Lopit, and, combined with the phonological and morphological analyses, significantly increase the level of description of an under-documented Nilo-Saharan language. This study also develops typological understandings of the phonetic implementation of ATR contrasts, the status of length distinctions among glides, and Nilotic tone systems, and demonstrates the value of incorporating phonetic data into the documentation of African languages.