ꞌBëlï Phonology, Tone and Orthography

ꞌBëlï, a Nilo-Saharan Language of South Sudan, uses tone as the only distinctive feature to differentiate meaning in nearly 20% of words. The functional load of grammatical tone is also very high in that at least seven prepositions are in tone minimal pairs with body part nouns, and three relative clause connectors are in tone minimal pairs with demonstratives. Even so, with four simple spelling rules, the ꞌBëlï are able to disambiguate 75% of lexical tone distinctions and all grammatical tone distinctions in writing. These rules essentially mark grammatical category rather than tone, and involve doubled vowels, underlined vowels, hyphens and commas.