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The labiodental flap /ⱱ/ is marginal, only occurring in two native Buwal words. The labial-velar plosives are also marginal; in particular, /kp/ only occurs in one word, the ideophonekpaŋ.
Buwal has the vowels /əa/, which can occur in high, middle, or low tone. Each vowel has a variety of phonetic realizations. /ə/ can occur as , and /a/ can occur as . The schwa can be analyzed as a solely epenthetic vowel. These vowels occur as roundedallophones when adjacent to a labialized consonant, and as front vowels when the word is palatalized.
Palatalization in Buwal occurs across an entire word, and also affects the affricate consonants /ts dz ⁿdz/, which surface as in a palatalized word. As a result, all of the vowels within a single word are either front or back, producing vowel harmony. An example of this contrast is between 'rat' (underlyingly /māⁿdwán/), which is non-palatalized, and (underlyingly /màvāɗvāɗāŋ/) 'turtle', which is palatalized. This process does not affect loanwords, e.g. 'oil' (from Fulfuldenebbam) or 'school' (from Frenchl'école). Some loanwords have been modified to accommodate Buwal phonology, e.g. 'tea', from Fulfulde sha'i.
Notes
^ Buwal at Ethnologue (18th ed., 2015) (subscription required)
Viljoen, Melanie Helen (2013). A grammatical description of the Buwal language (Ph.D. thesis). La Trobe University. hdl:1959.9/513436.
