Gradience is a concept that lies at the heart of phonetic and phonological variation change. This paper explores phenomenon nasalisation, process takes its origin in coarticulation that, as happened French, may lead to gradual development phonemic nasal vowels. We will discuss stages which this unfolded history French then zoom on Poitevin-Saintongeais region, where ancient vowel [ɛ̃jn] was reta...