Evaluation of sound field reproduction using the higher-order Mode Matching based on the equivalent sound source method

Many sound field reproduction technologies that physically reconstruct acoustic fields using multiple loudspeakers have been studied. One such method is the Mode Matching (MM) method, which determines the driving signals for loudspeakers so that the spherical harmonic expansion coefficients of the reproduced field match those of the target field. A key characteristic of this method is that the controllable region is determined by the truncation order of the spherical harmonic expansion, which depends on the number of microphones. Previously, we proposed an MM-based method that estimates higher-order expansion coefficients using a small number of microphones by modeling loudspeaker transfer functions based on the equivalent source method. Simulation experiments under free-field conditions demonstrated that the proposed approach achieves accurate sound field reproduction, even in the forbidden frequencies. In this study, we conduct experiments to evaluate the performance of the proposed method in real-world acoustic environments using an actual loudspeaker arrangement. We compare it with a conventional approach that directly derives spherical harmonic coefficients from microphone signals to assess the accuracy and robustness of sound field reproduction.