A Typological and Acquisitional Analysis of Tonal Systems in Nigerian Languages with Implications for L2 Phonology

Nigeria's linguistic landscape includes a remarkable diversity of tonal systems, ranging from the two-tone systems of many Bantu and Benue-Congo languages through the complex tonal morphophonemics of Yoruba and Igbo to the floating tone phenomena of Hausa, creating a rich natural laboratory for typological and acquisitional analysis of tone. This dissertation develops a typological and acquisitional analysis of tonal systems in selected Nigerian languages, making original contributions to tonal typology, L1 tonal acquisition, and the implications of L1 tonal experience for L2 English prosodic acquisition. The typological programme constructs a comparative analysis of tonal systems in twelve Nigerian languages representing five language families, examining tone inventory size, tone-bearing unit assignment, tonal morphophonemics, and downstep or downdrift phenomena using a consistent cross-linguistic descriptive framework. Three typological features not previously systematically documented in the Nigerian language family comparison literature are identified and described. The acquisitional programme presents two empirical studies: a cross-sectional L1 tone acquisition study examining Yoruba and Igbo tonal development in children aged two to seven using elicited production and perception paradigms, and an L2 prosodic acquisition study examining the effect of L1 tonal experience on the acquisition of English lexical stress by Yoruba, Igbo, and Hausa L1 learners. The L2 study reveals that Yoruba and Igbo L1 learners, whose L1 tones operate on syllable-level domains, show different L2 stress acquisition patterns from Hausa L1 learners whose tonal experience is more lexically distributed, a finding with implications for L2 phonology theory and English pronunciation instruction. Keywords: tonal typology, Nigerian languages, tonal acquisition, L2 phonology, prosodic transfer.