[1][2] Speakers of Kilmeri refer to their own language as bo apulyo, meaning sound in the middle.
The sounds in half brackets occur extremely rarely and can likely be attributed to loan words.
[6] It likely developed from a prenasalized bilabial stop followed by a high back rounded vowel, hence why [mbu] occurs only in ten words.
[3] Thus, Kilmeri was believed to have seven vowels[6] until a small selection of words, such as /bi/ (pig) and /bI/ (hole) show a clear distinction between /i/ and /I/.
Literate Kilmeri speakers much preferred the symbol p for the bilabial trill, but pp was selected to indicate two different phonemes.