This link will connect you to the phoneme inventory that is given for the Proto-Pray language in David Filbeck's article; "T'in a Historical Study." Filbeck acknowledges the fact that many Lua'/Pray dialects neglect the /r/ phoneme, but he includes the /r/ phoneme within the phonetic inventory of the Proto-Pray language. Filbeck, D. (1978). T'in: A historical study. Canberra: Dept. of Linguistics, Research School of Pacific Studies, Australian National University.