Crocodiles grunt, crickets chirp, hyenas laugh, chickadees twitter, grasshoppers stridulate. What secrets do these sounds conceal? Can we decipher their mysteries? What could animals be talking about? From Brazil to the North Sea, the Amazon rainforest to the Arctic's icy stretches, from the squeaking of young crocodiles to the noisy housting of elephant seals, biologist Nicolas Mathevon, a specialist in bioacoustics, explores the diversity of animal vocalizations. Join him and learn how these languages enable the expression of feelings, the choice of a partner, strategic trickery, struggles for dominance, the marking of territory, and calling for help.