This comparative study of the coordination of lip and velum movements during the articulation of the nasal consonant (m) in a symmetric vocalic context in French, and of the aerodynamic parameters associated with these movements, has provided evidence of the functioning modes of the velum and their dependence upon the nature of the vowel an its location with respect to the nasal consonant,. During the articulation of the vowel preceding the nasal consonant, the lowering of the velum is first accompanied by a decrease in the volume of air in the nasal passages. The subsequent increase in nasal air flow only occurs by the end of the preceding vowel and during the emission of the nasal consonant itself. However, the raising of the velum for the next vowel occurs in two stages: an initial fast rise during the first phase of the vowel, then a much slower rise during the final portion. This research sheds new light on our understanding of the relationships between the trajectories of lip and velum movements and the acoustic events that are associated with them.