The illustrations of illuminated manuscripts between 1300 and 1450 featured a very large number of animal musicians. They were set in the marginal borders of the pages, and framed the text and miniature with their musical sonorities. Along with King David, animals were the main musicians featured in medieval illuminations, far more numerous than angels and minstrels. The monkey, dog, fox and half-animal, half-human hybrid creatures were the " champions " of instrumental music. At the crossroads of history and art history, musicology and literature, their representations suggest that we identify typologies of books, animals and instruments. They raise several questions on three levels: 1/ the visual level of the instruments and instrumental practices represented 2/ then, the level of the cultural foundations of images and their rhetoric modus operandi 3/ finally, by adopting a synaesthetic approach to images and sounds to try to understand how to describe the sounds of instruments when they are " produced " by instrumentalists as peculiar as animals (sounds, noises, harmony, musica, silence?). This synaesthetic approach is also anthropological: as animals imitate human beings, what can be considered musical in both of them? What makes " musicality " and " sonority " criteria that allow us to distinguish and organise creatures in the order of God's creation in a hierarchy according to the medieval understanding of the world? I will discuss these questions from the perspective of the intellectual context: humanism present in princely courts, but also Aristotelianism and Neo-Platonism taught in European Colleges of Arts...