Attempt to improve the total performance of sound field reproduction system: Integration of wave-based methods and simple reproduction method

The sound field reproduction system can be applied to various applications. The primary objective of the system is to physically reproduce an arbitrary sound field correctly. However, physical accuracy is not the only requirement in a situation where the system is actually used. Through several applications, we assumed the following four factors as total performance; A) physical accuracy, B) robustness against disturbances, C) flexibility for additional direction, and D) capability of integration with visual media. We used 24-channel narrow directional microphone array and 24-channel loudspeaker as a platform to be considered and worked to improve overall performance. As one of the reproduction methods, directional information can be easily reproduced by amplitude panning which relies on the directivity of the microphone themselves, but the microphone leakage effect occurs in the low frequency. On the other hand, wave-based methods such as boundary surface control or higher-order ambisonics are effective for physical accuracy, but control of high frequency is difficult. Therefore, if wave-based method and simple reproduction method are combined, there is a possibility to reproduce a wide frequency range well. We discuss the total performance of this reproduction method through ITD/ILD measurement and visualization of a wide range of wavefront.