Predicting vowel backness variability in Tommo‐So.

Abstract

Tommo‐So (Dogon, Mali) has highly restrictive vowel phonotactics in stems. While any of its seven vowels may occur in the first syllable, the set of possible subsequent vowels is small, and noninitial nonlow vowels often exhibit a wide range of gradient variation in backness (while their phonological height remains fixed). Our study examines the second vowel of disyllabic words at all nonlow heights where (1) V1 = V2, (2) V1 is high and V2 is mid, and (3) V1 is mid and V2 is high, as well as the definite enclitic in various consonantal contexts. Preliminary acoustic analysis reveals that backness variation in V2 covers the whole range of front to back and yet is significantly less bimodal than would be expected if it were variation between discrete front and back allophones. Moreover, the majority of the variation cannot be attributed to coarticulation; that is, the same speaker will produce the same stimulus differently at different times. Nonetheless, if the first vowel is identical, variation is much restricted. We predict that grammatical morphemes such as the definite will display greater variation than lexical items.