Spatial accuracy of binaural synthesis from rigid spherical microphone array recordings

Binaural systems are a promising class of three-dimensional (3D) auditory displays for high-definition personal 3D audio devices. They properly synthesize the sound pressure signals at the ears of a listener, namely binaural signals, by means of the head-related transfer functions (HRTFs). Rigid spherical microphone arrays (RSMAs) are widely used to capture sound pressure fields for binaural presentation to multiple listeners. However, the spatial resolution needed in the RSMAs to allow for accurate binaural reproduction has not been studied in detail. The aim of this paper is to objectively address this question. We evaluated the spatial accuracy in binaural signals synthesized from the recordings of RSMAs with different number of microphones using the model of a human head. We find that the synthesis of spectral cues is accurate up to a maximum frequency determined by the number of microphones. Nevertheless, we also identify a limit beyond which adding more microphones does not improve overall accuracy. Said limit is higher for the interaural spectral cues than for the monaural ones.