This paper provides an optimality - theoretic account on lowering of nasal vowels in French from a (functional and) phonetic viewpoint. I will first claim that nasal vowel lowering in French was initiated by nasalization of a high vowel, in which the first formant (Fl) of /i/ (or/y/) was elevated by prominent nasal acoustic energy. Second, I will argue that the subsequent lowering of tense vowels le, y, 01 to [a, re, 5] is a consequence of dispersion of contrast between adjacent vowels, for which we evaluate a sequence of relevant adjacent vowels, rather than individual vowels in isolation. Third, I will discuss a case of neutralization in len, an/-+l iiI change, a challenging case to the dispersion pattern of contrast. I will argue that the final output of the nasal vowel pattern is a consequence of constraint interactions. We will
also observe that there is a strong tendency that we maintain the closest formant values of the inputs in the outputs as possible. This result is also obtained by the pattern evaluation of the adjacent vowels. Fourth, I will discuss possible theoretical problems in a rule-based approach, in comparison with the consequences in our current analysis. Finally, I will add a theoretical implication of the result in relation to the functional goals of Dispersion Theory (Lindblom 1986, Flernrning 1996)
