Model Matching Control for Binaural Reproduction over Loudspeakers

In this paper, we address a design method of binaural sound reproduction over loudspeakers, which is a virtual realization of three-dimensional audio. The reproduction is achieved by a model matching control to reproduce a desired sound field in a reproduced sound field. It is known that any sound field includes unstable zeros that are originated from the inherent propagation delay. Therefore, the model matching controller including the direct inversion of the reproduced sound field is inevitably unstable and cannot be implemented to actual systems. To avoid this instability, we propose a design method of a stable feedforward controller based on an H8 model matching problem. Additional low gain specification is imposed on the controller to enhance the robustness against modeling errors of the sound field. We apply the design method to actual experimental data of a sound field and also demonstrate through a numerical experiment that the designed controller realizes binaural reproduction accurately.