The role of source signal similarity in distinguishing between different positions in a room

Typically, evaluation of spatial audio systems uses the same source signal for each condition in listening comparison tests (such as ABX and MUSHRA). However in an augmented reality scenario, it is unlikely that the exact same source signal would exist at the exact same position in space, both real and virtual: instead, a real source would be in one position in the room and a virtual source in a different position, both with different source signals. A perceptual study is presented on the effect of source signal similarity when distinguishing different positions in a room. Three source signal types (all speech) are investigated in a multiple stimulus paradigm: the same source signal for all conditions, the same speaker but a different sentence for each condition, and a different speaker and different sentence for each condition. Results show that the source signal similarity significantly impacts the similarity rating between different receiver positions in the same room, which suggests that spatial audio system fidelity requirements could vary depending on the source signal types used in the target application.