  In this study, we propose the use of virtual urban field studies (VUFS)
through context-based interface prototypes for evaluating the interaction
design of auditory interfaces. Virtual field tests use mixed-reality
technologies to combine the fidelity of real-world testing with the
affordability and speed of testing in the lab. In this paper, we apply this
concept to rapidly test sound designs for autonomous vehicle (AV)--pedestrian
interaction with a high degree of realism and fidelity. We also propose the use
of psychometrically validated measures of presence in validating the
verisimilitude of VUFS. Using mixed qualitative and quantitative methods, we
analysed users' perceptions of presence in our VUFS prototype and the
relationship to our prototype's effectiveness. We also examined the use of
higher-order ambisonic spatialised audio and its impact on presence. Our
results provide insights into how VUFS can be designed to facilitate presence
as well as design guidelines for how this can be leveraged.
