The Vai language of Liberia and its syllabic script have recently been
receiving some attention because there is now a formal proposal for
encoding it in Unicode ( ).

Looking at the repertoire, it was striking that contrastively nasal
vowels only follow glottal, labiovelar (*co-articulated*) or velar
consonants. It was also striking that the full set of possibility
only occurs after glottal consonants. (I discount w~ because that set
was originally intended for /W/.) For simplicity in the analysis, I
have assumed that syllables begin with a consonant, be it only a
glottal stop.

Nasal consonants are always followed by nasalised vowels, so I would
describe these vowels as non-contrastively nasal.

Does anyone here know the origin of the restriction on the occurrence
of nasal vowels? It seems to be related to the phenomenon of
rhinoglottophilia. One possibility (from my position of almost total
ignorance) is that rhinoglottophilia is inhibiting a process of