Sociolinguistic Variation in Educated Nigerian English: Vowel Variables Across the Six Geopolitical Zones

Educated Nigerian English (ENE) is frequently described as a relatively uniform national variety in contrast to the more markedly regional and ethnic varieties of Nigerian English, yet fine-grained sociolinguistic investigation of its phonological variability across geopolitical zones has been limited by the logistical challenges of large-scale cross-national acoustic data collection. This study investigates vowel variability in Educated Nigerian English across the six geopolitical zones, examining four vowel variables in the speech of educated speakers with standardized sociolinguistic backgrounds. One hundred and eighty participants, thirty from each geopolitical zone, were recruited through universities, with each participant completing an interview, a word list reading, and a minimal pair reading task. Acoustic analysis of F1-F2 formant trajectories for four target vowels, TRAP, DRESS, STRUT, and LOT, was conducted in Praat, with Lobanov normalization applied to control for inter-speaker anatomical variation. Analysis of variance reveals statistically significant zone effects for all four vowels, with TRAP and DRESS showing the largest geographic variation. South West zone speakers consistently produce front vowel realizations closer to Received Pronunciation targets, while North West zone speakers show the most raised TRAP and raised STRUT productions. South South speakers show the most distinctive LOT realization, with a backed-and-rounded production differentiating them from all other zones. The findings demonstrate that geopolitical zone accounts for a significant and previously underdocumented proportion of ENE phonological variation. Keywords: educated Nigerian English, vowel variation, sociolinguistics, geopolitical zones, acoustic phonetics.