bull-roarer, an instrument consisting of slit board or chamber attached to a cord. When swung around in the air, it emits a deep, vibrant, "whirrrrrr"-like sound. The mythology of some Native South Americans (e.g., the Tupí-Guaraní) indicates that women originally controlled such sacred instruments of power as bull-roarers, flutes, or trumpets, but, through some calamity (often involving women's inability to hunt), lost possession of these instruments to men. The control of such instruments legitimizes adult male power. Thus, at puberty, Bororo boys are shown how to use bull-roarers, and they participate in secret rituals with the adult men. There are separate ceremonies in which men taunt women with bull-roarers, sexual songs, and clay phalluses. Taboos exist against women seeing these instruments, which are normally concealed in the men's house but removed for ceremonies. Women's real attitude toward bull-roarers is difficult to gauge; some secretly admit to have seen the sacred instruments, but open defiance of the taboos would invite severe sanctions and is avoided. Among some groups, the instrument is merely a toy. The bull-roarer is also important among the Australian aborigines. See matriarchy.