Investigation of the Minimum Required Spatial Resolution of Moving Sound Sources

Sound field synthesis and manipulation in the Spherical Harmonics (SH) domain has become an established method in research and the consumer sector. The maximum order of the sound field SH representation is associated with the maximum spatial resolution of the virtual acoustic environment. The influence of the spatial resolution (SH order) of single non-moving sound sources has been investigated intensively in previous studies, and the minimum spatial resolution, which is indistinguishable from a high spatial resolution, has been determined. In real-life scenarios, however, sound sources may also move in the presented sound scene. So far, it has barely been studied whether and how the minimum perceptible spatial resolution changes for moving sound sources. This work presents a listening experiment applying dynamic binaural synthesis and examining the minimum required spatial resolution of moving sound sources. Participants compared SH order-limited anechoic sound sources moving with a fixed speed and distance with the same sound sources rendered at an order of 35. Using an ABX test design, we determined the threshold of indistinguishability. The results show that moving sound sources require significantly lower SH orders than non-moving sound sources.