Frication and formant frequencies in the Mundabli high vowels

International audience Mundabli (Yemne-Kimbi, Cameroon) is reported to contrast two sets of high vowels: extra-high /i u/ and high /ɪ ʊ/, by way of frication intrinsic to /i u/. In this study, we assess the role of aperiodicity (zero crossing rate, ZCR) and formant frequencies (midpoint F1-F2) in these contrasts. Analysis of the dynamics of ZCR in the vowels of interest using generalized additive mixed models shows elevated aperiodic energy early in the duration of /i u/ compared to /ɪ ʊ/, modulated by onset consonant type. Small, inconsistent differences in F1 and F2 are observed, and /i/ tends to exhibit lower F2 than /ɪ/, suggesting that this contrast is not simply one of height. These findings contribute to our understanding of the fricative vowels and their development from plain high vowels; and add to the literature on vowel contrasts involving frication.