This article presents the results of a study based on a group of participants' interactions with an experimental sound installation at the National Science and Media Museum in Bradford, UK. The installation used audio augmented reality to attach virtual sound sources to a vintage radio receiver from the museum's collection, with a view to understanding the potentials of this technology for promoting exploration and engagement within museums and galleries. We employ a practice-based design ethnography, including a thematic analysis of our participants' interactions with spatialised interactive audio, and present an identified sequence of interactional phases. We discuss how audio augmented artefacts can communicate and engage visitors beyond their traditional confines of line-of-sight, and how visitors can be drawn to engage further, beyond the realm of their original encounter. Finally, we provide evidence of how contextualised and embodied interactions, along with authentic audio reproduction, evoked personal memories associated with our museum artefact, and how this can promote interest in the acquisition of declarative knowledge. Additionally, through the adoption of a functional and theoretical aura-based model, we present ways in which this could be achieved, and, overall, we demonstrate a material object's potential role as an interface for engaging users with, and contextualising, immaterial digital audio archival content.