Dynamic binaural Ambisonics scheme for rendering distance information of free-field virtual sources

One object of dynamic binaural rendering is to recreate virtual source in various directions and distances in headphone reproduction.A simplified signal processing scheme for recreating directional and distance information in dynamic binaural rendering is presented in this work.The signal processing scheme includes two steps.The first step is to synthesize the loudspeaker signals in near-field Ambisonics for reconstruction of target sound field by using spherical harmonics functions decomposition and each order approximation.The second step is to convert the Ambisonics signals for loudspeaker reproduction into the binaural signals for headphone reproduction using the dynamic Head-Related Transfer Function(HRTF) -based binaural synthesis or virtual loudspeaker method.The effects of the order of binaural Ambisonics on localization performance in reproduction were further investigated to provide guidance for simplifying the scheme.Analysis on the binaural pressures in reproduction indicated that the 5th dynamic binaural Ambisonics reproduction was adequate to provide major information for directional localization and distance perception.Psychoacoustic experiment proved that,combined with distance-dependent loudness cue,the 5th dynamic binaural Ambisonics reproduction was able to recreate the auditory perception of virtual at various directions and distance closer than 1.0 m.The present scheme only requires non-individualized HRTFs at a constant far-field distance and 48 uniform directions for binaural synthesis and thereby simplifies the signal processing.