Gwari has 3 level tones. Hyman and Magaji note
that "one distinctive characteristic of all Gwari dialects
is the presence of consonant + nasal clusters". An
alternative would be to posit 3 nasalized vowels, but H &
M's analysis is accepted here, since C + N + /a/ is
realized as consonant + nasal release + oral vowel [a].
High vowels /i,u/ after C + N are phonetically nasalized,
and C + N + /i/ only has a phonetic nasal consonant
segment if C is bilabial or velar. A loose end is a
grammatical particle (orthographic 'in') which is a
nasalized vowel only. /t,d,s,z/ are palato-alveolar
affricates and fricatives before front vowels or /j/. /n/
is palatal before /j/ and velar before /w/.

Hyman, L. and Magaji, D. 1970. Essentials of Gwari
Grammar. Institute of African Studies, University of
Ibadan, Occasional Publication No. 27.