“Music’s Material Dependency: What Underwater Opera Can Tell Us about Odysseus’s Ears” examines the underwater vocal practice of Los Angeles–based performance artist and soprano Juliana Snapper and dispenses with the idea that sound is stable and knowable before it is produced and perceived. By displacing air as the natural medium through which sound materializes, and by recognizing instead that airborne sound partakes of air’s distinctive features, we come to appreciate the process of sound as a dynamic, interactive coming into being. This chapter also applies Snapper’s insights to a new reading of the sirens in Homer’s Odyssey. Overall, this study discourages the common understanding of sound as merely aural and exposes the associated deficiencies in current analytical techniques.