On the Status of Bìrọ̀m Vowel Harmony

Platoid languages of North-Central Nigeria, including Bìròṃ, have been assigned to an “ATR-less zone” in which tongue root harmony is held to be absent, and the only recognized mid-vowel patterning is one of strict or liberal contrast. This classification, however, rests on typological generalization rather than on instrumental evidence. This study therefore sets out to determine the status of vowel harmony in Bìròṃ by examining the co-occurrence patterns of mid vowels to establish whether they constitute a harmony system and to identify the acoustic cues that characterize the behavior of that system. Fifty-five CVCV lexical items were elicited from ten adult native speakers, with each item repeated three times, yielding 1,650 tokens. The data were annotated in ELAN, measured automatically in Praat, and analyzed in RStudio and PhonR. F1, F2, B1, and CPP were measured, and the analysis was framed within the typology of ATR harmony - particularly the distinction between complete and trace (incomplete) systems. Findings show that Bìròṃ operates a trace ATR system in which height and tongue root interact, such that [+ATR] mid vowels do not co-occur with [-ATR] mid vowels within the root, while the high and low vowels /a i u/ remain neutral. Acoustically, [-ATR] vowels have consistently higher F1 and B1 than their [+ATR] counterparts, whereas F2 separates the back pair [o] and [ɔ] from the non-back pair [e] and [ɛ], a difference attributable to backness rather than tongue root position. These findings are consistent with articulatory explanations from previous acoustic investigations.