Development of an auditory virtual reality system based on pre-computed B-format impulse responses for building design evaluation

Abstract

This study presents an auditory virtual reality system which relies on pre-computed B-format impulse responses in a grid across the domain. Spatial information is encoded in the impulse responses by means of higher order Ambisonics and decoded to a virtual loudspeaker array, which follows the listener during run-time. The impulse responses are convolved with source signals, played back through the virtual loudspeaker array and synthesized for binaural headphone reproduction through head related transfer functions. This approach allows for a completely free movement and orientation of the listener in the virtual scene. Furthermore, it allows for the usage of highly accurate offline simulations of room impulse responses. The system is validated with two listening tests. First, the sound source localization performance in virtual reverberant rooms is tested while varying the order of Ambisonics, visuals and head movement. Second, the effects of the grid resolution on the perceived realism, sound source size and sound continuity are investigated. The results reveal that when using second order Ambisonics, together with visuals and allowing head movement, the localization error is very low, being less than one just-noticeable difference. Furthermore, when using a coarse grid, the perceptual sound source size is increased and spread out. Perceived realism and sound continuity are not significantly affected by the grid resolution. Two video files that show the proposed system in use are provided.