Challenges, ad-libs, games and quarrels form part of a long tradition. All these cultural manifestations derive from "explosive" performances. In Portugal, these eruptions feature in country dances, disputes, Azorean folkdances, singsongs ... and within fado music itself (desgarradas or competitive impromptu singing). Musical competitions also emerge in the St John festivities that the Portuguese took to Brazil. Improvisation-based performances like these will be examined within the universe of fado music. "Volatile" and "mimetic" variations associated with fado are the object of this study, taking into account the wide geographical range of influences on fado music (from Arabic to Afro-Brazilian influences). The project will involve the use of documental sources and audio-visual recordings.