For several years, the group Les Cris de Paris have collected songs from oral traditions from all around the world. With the complicity of composer Pierre-Yves Macé, today they revisit the acappella songs they have collected in an enthralling instrumental, vocal and electroacoustic composition. The work raises the question of polyphony: how can we allow these heterogeneous sources to cohabitate or come together? The work consists of three cantatas, each very different in their instrumentation, and responds to the challenge of heterogeneity by various strategies such as fragmentation, free association and the intertwining of sources. The result is an aesthetic cosmopolitanism, beneficial at a time when walls are being erected at borders.