Binaural reproduction of dummy head and spherical microphone array data—A perceptual study on the minimum required spatial resolution

Abstract

Dynamic binaural synthesis requires binaural room impulse responses (BRIRs) for each head orientation of the listener. Such BRIRs can either be measured with a dummy head or calculated from the spherical microphone array (SMA) data. Because the dense dummy head measurements require enormous effort, alternatively sparse measurements can be performed and then interpolated in the spherical harmonics domain. The real-world SMAs, on the other hand, have a limited number of microphones, resulting in spatial undersampling artifacts. For both of the methods, the spatial order N of the underlying sampling grid influences the reproduction quality. This paper presents two listening experiments to determine the minimum spatial order for the direct sound, early reflections, and reverberation of the dummy head or SMA measurements required to generate the horizontally head-tracked binaural synthesis perceptually indistinguishable from a high-resolution reference. The results indicate that for direct sound, N = 9–13 is required for the dummy head BRIRs, but significantly higher orders of N = 17–20 are required for the SMA BRIRs. Furthermore, significantly lower orders are required for the late parts with N = 4–5 for the early reflections and reverberation of the dummy head BRIRs but N = 12–13 for the early reflections and N = 6–9 for the reverberation of the SMA BRIRs.