Acoustic Analysis of Nigerian English Vowels: A Comparative Phonetic Study of Educated and Non-Educated Speakers

Nigerian English (NE) displays notable phonetic diversity, particularly in its vowel systems, shaped by the interplay of indigenous languages, social factors, and formal education. While prior research has extensively examined major NE varieties such as Yoruba, Hausa, and Igbo English, less attention has been given to minority sub-varieties, including Tiv and Urhobo English. This study presents a comprehensive acoustic investigation of vowel production in educated and non-educated speakers of these underexplored varieties, aiming to understand how formal education and social exposure influence vowel realization. A total of forty native NE speakers participated, evenly split between educated individuals (holding at least a bachelor’s degree) and non-educated individuals (with primary or secondary education). Speech samples were collected through word lists and controlled sentences in quiet settings and analyzed using Praat software to measure vowel formants (F1, F2, F3), duration, and spectral features. Findings reveal systematic differences: educated speakers produced vowels closely aligned with Standard British English norms, whereas non-educated speakers exhibited vowel centralization, reduction, diphthong simplification, and substitutions influenced by their first languages. Specifically, monophthongs such as /iː/ and /ɔː/ were altered in non-educated speech, while diphthongs like /eɪ/ and /aɪ/ often became monophthong zed. Vowel duration was generally longer in educated speakers, contributing to perceptible differences in intelligibility and prosody. These results suggest the emergence of a socially stratified NE vowel system and underscore the significant role of education and social experience in shaping vowel production. The study expands our understanding of NE phonology and highlights the need to include speakers from diverse educational and regional backgrounds in future phonetic and sociolinguistic research.