The study of oral tradition of music permits discussing the question of the organization of musical syntax and reference systems in an interesting way. These musical systems are sometimes acquired without explicit teaching, as Pygmies polyphonies from Central Africa. When more explicit they are often based on non-verbalized knowledge. The organization of African polyphonies is based on a few simple principles to constantly renew the musical discourse and to create a very complex musical structure. The principles of simple melodic and rhythmic variations (swap intervals or changing the internal structure or rhythmic cells) are used to build a musical discourse of great complexity and which seem, at first sight, largely self-organized. The presence of similar musical structures in different places of the world, e.g. Hoquetus in polyphonic music, raises the question of universals in music. The musical scales taken outside of constructed systems pose the issue of possible auditory constraints.