Acoustic Phonetic Analysis of Vowels in Ijaw: A Study of Izon Dialect Speakers in Bayelsa State

This study presents an acoustic phonetic analysis of the vowel system of the Izon dialect of Ijaw as spoken by residents of Yenagoa and surrounding communities in Bayelsa State, South South Nigeria. The Ijaw language family, despite its demographic and cultural significance in the Niger Delta, has received limited modern acoustic phonetic documentation, and the vowel system of the Izon dialect specifically has not been subjected to instrumental analysis. The research adopts an experimental phonetic methodology using Praat acoustic analysis software. Forty native Izon speakers, balanced for gender and age cohort, produced controlled word list items containing target vowels in consistent consonantal environments. Formant frequency measurements for F1, F2, and F3 were extracted from midpoint tokens, and vowel space plots were constructed and compared across speaker groups. Findings confirm a ten-vowel oral vowel inventory for Izon, with consistent evidence for advanced tongue root harmony as a phonological process affecting vowel quality in adjacent morphemes. Gender-based acoustic differences in formant frequencies are documented and discussed in relation to vocal tract anatomy and socialisation effects. The study provides the first acoustic phonetic dataset for Izon vowels and contributes to the phonological documentation of Niger Delta languages, with implications for literacy material development and speech technology applications. Keywords: acoustic phonetics, vowels, Izon, Ijaw, Bayelsa State.