Dialectal Intelligibility Among Igbo Speakers: An Experimental Study Across Five Regional Varieties

This study investigates mutual intelligibility among speakers of five regional varieties of Igbo through a controlled experimental design, generating the first quantitative cross-dialectal intelligibility matrix for the Igbo language. The degree of mutual intelligibility across Igbo dialectal varieties has been debated in applied and theoretical linguistics without empirical resolution, with some scholars arguing for a high intelligibility continuum and others documenting significant communication difficulty across geographically distant varieties. The research recruits two hundred native speakers, forty from each of the Owerri, Onitsha, Nsukka, Ika-Delta, and Ezza-Ebonyi dialect regions. Intelligibility is assessed through a battery of three tasks: word recognition from audio stimuli, sentence repetition accuracy, and narrative comprehension summary scores. All stimuli are produced by speakers of unfamiliar dialects and responses are scored for accuracy by trained raters blind to participant variety. Acoustic analysis identifies specific phonological and lexical variables that predict intelligibility difficulty. Findings reveal an asymmetric intelligibility pattern, with Central Igbo varieties (Onitsha and Owerri) showing significantly higher reception scores for other dialects than peripheral varieties such as Ika-Delta and Ezza-Ebonyi. Tone and vowel harmony variation rather than lexical divergence are found to be the primary sources of intelligibility difficulty. The study provides evidence-based implications for Igbo language standardisation policy and dialect-sensitive pedagogy. Keywords: Igbo dialectal intelligibility, experimental linguistics, dialect variation, mutual intelligibility, Igbo varieties.