The present article aims at analyzing the social and ontological effects of listening music online, with particular attention to the artistic practice of improvisation. In the first paragraph, I will briefly explain the essential concepts which ontology of music has traditionally counted on, and I will suggest an alternative theoretical approach, that I define as ontology of musical act. Then I will investigate the relation between recording practices and improvisation. In the final paragraph I will compare some features of musical (...) recordings with those of technological devices that allow us to listen music online. (shrink)