ATR vowel harmony is a common feature in African languages that has received massive scholarly work. Although some of these languages have both phonemic oral and nasal vowels, only the oral vowels usually feature in descriptions and analyses. Also, although some of these languages have phonemic nasal vowels, Rolle (2013) notes that phonemic /ẽ, õ/ nasal vowels are missing in some West African languages. He notes further that, earlier, Hyman (1972) had observed that [n] (and sometimes [m] does not occur before mid vowels), hence the restricted patterns *[ne]~*[nẽ] and *[no]~*[nõ]. If these vowels are barred and their possible occurrences are restricted, are there other means for them to be realized in these languages? In this paper, I present data on the interactions between ATR vowel harmony and nasality in Gua (a Guang language of Ghana) and shows that nasal vowels fully participate in the harmony process, and where nasal vowels /ẽ, õ, ɜ̃/ are missing, they are created allophonically [ẽ, õ, ɜ̃] via ATR vowel harmony, nasalization and a combination of both processes in the language. This is similar to harmony patterns in African languages where missing oral vowels in seven vowel systems are created allophonically (Rose 2018 and Casali 2003). I further discuss some typological implications of the patterns and useful questions that will guide further research in these interactions.

References cited:
Casali, R. F. 2003. [ATR] value asymmetries and underlying vowel inventory structure in Niger-Congo and Nilo-Saharan. Linguistic Typology 7, pp. 307-382
Hyman, L. M. 1972. “Nasals and nasalization in Kwa”. Studies in African Linguistics, 3.2, pp. 167-205.
Rolle, N. 2013. Nasal vowel patterns in West Africa. UC Berkeley PhonLab Annual Report 9.9.
Rose, S. 2018. ATR Vowel Harmony: new patterns and diagnostics. In Proceedings of the 2017 Annual Meeting on Phonology (Vol. 5).