Impact of direct-to-reverberation ratio and interaural cross-correlation on externalization in binaural audio rendering

Abstract

To achieve realistic binaural reproduction of spatial audio in a headphone scenario, addressing inside-the-head-locatedness is crucial, which can be accomplished through appropriate externalization techniques. Two acoustic cues, the direct-to-reverberation ratio (DRR) and interaural cross-correlation (IACC), are known to influence perceived externalization. However, the precise relationship between these cues and their combined effect has not been extensively studied. In this investigation, we aim to explore the relative contribution of DRR and IACC to externalization by examining various combinations of these two acoustic cues. To this end, participants were exposed to various binaural room impulse responses (BRIRs) synthesized to produce three distinct levels of DRRs and IACCs for two different source directions. The listening test was conducted in an anechoic chamber with participants’ eyes blindfolded to minimize the influence of room divergence effect. We also investigated the influence of head tracking by conducting experiments with and without head trackers. The correlation maps between externalization and the two acoustic cues were generated for each source direction. The study reveals that the contribution of the two acoustic cues differs with and without head tracking, and the joint contribution also varies depending on the source direction and amount of reflections included in the BRIR.