This article deals with the changes that have come about in the description of musical knowledge and with the ensuing needs in this field in the era of decentralisation. Through the Net we can, on the one hand, replace, manipulate and recontextualise musical parameters until a different significance emerges; at the same time, randomising and hybridising musical objects can partially change our perception of the same musical events. On the other hand, music online databases, audio browsers and musical queries may open the way to overthrowing, reorganising and personalising music description. This could occur at different levels and to different degrees of complexity, both as a social event and as an active, user-based combination of musical structures.