A study on 3-D Sound Field Localization System Using Parametric Loudspeaker and Indirect Loudspeakers for Reverberation Reproduction

3-D sound field reproduction systems can provide listeners with a sense of presence. In this study, we have proposed the 3-D sound field localization system using parametric loudspeakers. This system can easily represent sound images on the wall by using parametric loudspeakers that have a high directivity. In contrast, it is difficult to reproduce reverberant environments such as a concert hall because the parametric loudspeaker can hardly represent a reverberation. In the former system, therefore, we add the reverberation and control the reverberation time by using indirect electrodynamic loudspeakers. However, it can imperfectly reproduce reverberant environments because the reverberant characteristic is not only the reverberation time. In this paper, we newly propose the 3-D sound field localization system using the parametric loudspeaker and indirect electrodynamic loudspeakers for the reverberation reproduction. Specifically, in the reverberation reproduction, we design inverse filters of transfer functions between listening points and indirect electrodynamic loudspeakers. Then, we reproduce the desired reverberant environment by emitting signals convoluted with inverse filters and the impulse response in the desired sound field from indirect electrodynamic loudspeakers. As a result of the objective experiment on the performance of the sound image localization and the reproducibility of the reverberation, we confirmed the effectiveness of the proposed system.