Experimental evaluation of bilateral Ambisonics-based binaural room transfer function synthesis with application to personal sound zones

This study experimentally evaluates the bilateral Ambisonics method for synthesizing binaural room transfer functions (BRTFs) and explores its application in generating personal sound zones (PSZs) around listeners’ ears. Bilateral Ambisonics is proposed for improving the spatial sound reproduction accuracy at a limited Ambisonics order, by shifting the origin of Ambisonics representation from the head center to the two ears. While numerical simulations have demonstrated its superiority over traditional Ambisonics, little attention has been given to validating its usability for reproduction in realistic environments with loudspeakers. Experiments are conducted wherein the BRTFs of a dummy head listener are first synthesized by combining the spatial room transfer functions (SRTFs) measured with a spherical Ambisonics microphone array at the ear position and the corresponding head-related transfer functions (HRTFs), and then compared with the actual in situ measured ones. Furthermore, the quality of the synthesized BRTFs is examined in the context of an in-house PSZ system, by objectively evaluating the performance of PSZ filters designed with such BRTFs in terms of acoustic isolation metrics. The application of synthesized BRTFs to PSZ systems circumvents the need for in-situ BRTF measurements, making it highly feasible to deploy such systems while achieving high acoustic isolation.