In this paper, we discuss the positive heuristic potential of two Brazilian discourse theories: the first one is Semiotics of the song, by the Brazilian researcher Luiz Tatit; the second one is the Theory of basic stereotypes and opposed stereotypes, by the Brazilian researcher Sírio Possenti. The first theory, on one hand, is based on the preparation of a complete concept for a systematic study of Brazilian songs considering the meeting of melody and lyrics. The Semiotics of the Song Theory presents an isotopic analysis of elements of content and expression, in which melody and lyrics are taken as equivalent structural elements. The researcher Tatit, in his studies, relates aspects of expression to aspects of content in various Brazilian popular songs. He comprehends that Brazilian songs may be assigned to three major types: thematized, passionalized and figuretivized.