Listening to music on personal, digital devices while mobile is an enjoyable, everyday activity. We explore a scheme for exploiting this practice to immerse listeners in navigation cues. Our prototype, Ontrack, continuously adapts audio, modifying the spatial balance and volume to lead listeners to their target destination. An initial lab-based evaluation has demonstrated the approach's efficacy: users were able to complete tasks within a reasonable time and their subjective feedback was positive. Encouraged by these findings, we are building a pocket-sized prototype for further testing. Author Keywords Mobile systems, navigation, audio, ambience, GPS. ACM Classification Keywords H5.5. Sound and music computing.