Nyole has an interesting development from Proto-Bantu *p → Nyole /ŋ/. Schadeberg (1989) connects this sound change to rhinoglottophilia, where the sound change developed first as *[p] → [ɸ] → [h]. Then, given the acoustic similarity of [h] and breathy voice to nasalization, the sound change progressed as [h] → [h̃] → [ŋ]. The velar place of articulation development is due to velar nasals being the least perceptible of the nasals and its marginal status in (pre-)Nyole and other Bantu languages. In closely related neighboring languages, *p developed variously into /h/ or /w/ or was deleted.
This historical development results in so-called "crazy" alternations, like /n/ + /ŋ/ resulting in /p/ as in the following:
n-ŋuliira ("hear" stem form) : puliira "I hear"
n-ŋumula ("rest" stem form) : pumula "I rest"
In the above two words, when the first person singular subject prefix /n-/ is added to the stem starting with /ŋ/, the initial consonant surfaces as /p/. In other forms (like /oxu-ŋuliira/ "to hear" and /oxu-ŋumula/ "to rest"), the original stem-initial /ŋ/ can be seen.