Impairments of Binaural Sound Based on Ambisonics for Virtual Reality Audio

This paper is concerned with impairment of binaural sound that is reproduced through headphones based on ambisonics for virtual reality (VR) audio. Ambisonics is widely used for recording and reproducing ambient sound fields in VR audio, and in practice, the first or second order of ambisonics is used. However, in physical point of view, these orders are not enough to accurately reproduce sound at ear positions, and thus the binaural reproduction has inherent artefacts in terms of spectrum and sound localization. This paper analyses these artefacts with the first order ambisonics by using sound at ear positions of a rigid sphere that models a listener's head. Three virtual loudspeaker layouts are employed to investigate the effect of the layout. The results show that impairments in spectrum depends on the number of the virtual loudspeakers, and reproduced inter-aural level differences (ILDs) are not sufficient with any of these layouts.