Externalization improvement in a real-time binaural sound image rendering system

In binaural sound image rendering applications, it is very important to display virtual sound source out-of-head. However, the traditional methods depending only on the Head Related Transfer Functions (HRTFs) always result in a feeling that virtual sound source is located inside the listener´s head. In this paper, a real-time binaural sound image rendering system is built, which involves several important factors related to sound propagation, such as image-based early reflection and artificial late reverberation, etc. We also use head-tracker to dynamically determine the relative direction of virtual sound source. The necessary order of early reflection and the effect of late reverberation are studied as well. The subjective listening tests show that the 2nd-order early reflections are more helpful than late reverberation. When combining both early and late reflections, the externalization performance is significantly improved. The sound direction determination is preserved as well.