This article is concerned with the ritualization of sexual antagonism in Amazonia through an analysis of ethnographic data from the Matis, a Panoan-speaking group. More specifically, it analyzes the small repertoire of sounds and shouts which men and women use in certain ritual contexts, arguing that they form a system which should be interpreted in light of the sexual complementarity and generalized transformability which is characteristic of Ame- rindian cosmologies. Finally, it hopes to contribute to the recently revisited debates among Americanists and Ocea-nists, who find in flute complexes, masks and the cults with which they are associated, a common theme.