Shared and Divergent Phonological Processes in The Numeral Systems of Urhobo and Edo

This study presents a comparative phonological analysis of the numeral systems in Urhobo and Ẹdo, two closely related Southwestern Edoid languages spoken in southern Nigeria. The primary aim is to identify and analyse both shared and language-specific phonological processes involved in the formation of cardinal numerals, with particular attention to processes triggered during numeral compounding. Drawing on data elicited from native speakers, the study employs a descriptive-comparative method complemented by the theoretical framework of Autosegmental Phonology, which allows for the representation of tonal and segmental features on separate tiers. Analysis reveals that both languages exhibit several shared phonological strategies, including vowel elision, glide formation, nasalisation, and tonal assimilation. These processes are especially prominent at morpheme boundaries, where they serve to maintain syllable harmony and resolve hiatus, with vowel elision emerging as the most frequent strategy in both systems. However, notable divergences also surface: Urhobo demonstrates a process of vowel backing, whereby front vowels are retracted under specific phonological conditions, while Ẹdo exhibits tonal downstep, a pitch-lowering phenomenon arising from floating low tones following vowel deletion. These differences underscore each language’s unique phonological evolution, even within a shared typological framework. The findings contribute to the documentation and comparative analysis of under-researched numeral systems and offer broader implications for understanding phonological variation within the Edoid language group.