Birds of a Feather Augment Together: Exploring Sonic Links Between Real and Virtual Worlds in Audio Augmented Reality

Augmented reality (AR) applications present virtual elements that are connected to the real world. While these may be aware of a user's geographical or visual context, the real sounds in a user's environment are rarely used in the AR experience. We investigate audio augmented reality (AAR) with sound as the primary output. We present the first evaluation of sonic linking, where an AAR application uses real sounds (bird calls and car engines) in a user's surroundings to drive the interaction. We developed two AAR applications to investigate how to design and use such links: a game where entities are spawned based on real-world sounds and a music player with sound-reactive filtering and volume adjustment. Design variations are compared to cover different AAR scenarios, types of sonic link, and existing unlinked equivalents. The results show that sonic linking can create a more augmented, engaging AAR experience, and may alter a user's relationship with their real-world surroundings, enabling new types of augmented reality applications.