In this paper we examine how the term 'Audio Augmented Reality' (AAR) is used in the literature, and how the concept is used in practice. In particular, AAR seems to refer to a variety of closely related concepts. In order to gain a deeper understanding of disparate work surrounding AAR, we present a taxonomy of these concepts and highlight both canonical examples in each category, as well as edge cases that help define the category boundaries. CCS CONCEPTS • General and reference → Surveys and overviews; General literature; • Human-centered computing → Mixed / augmented reality.