Sound field reproduction by using a scatterer

This study proposes a method to reproduce a sound field that we desire in a selected control region by using an array of loudspeakers, both temporally and spatially. The desired sound field means a sound field that we can have in concert halls and stadiums, or that we want to have for special effects in movies and computer games. If a sound field that is identical to the desired field is generated by using loudspeakers, one who is in the field will have the same feeling as that in the desired field. In other words, this study aims to mimic the desired field in a control region so as to make listeners feel as if they were in the desired field. The proposed method uses a scatterer on the surface of which microphones are mounted to measure the surface pressure. Then, by using the measured pressure, the input signals to loudspeakers are obtained that makes the reproduced field identical to the desired field in the control region. In other words, if we put the scatterer in any sound field, and measure the surface pressure, then we can reproduce the sound field by loudspeakers. This method is based on the fact that the pressure on the surface of a scatterer uniquely determines the incident sound field which is generated if the scatterer is not placed. The use of the scatterer enables us to reproduce sound fields at all frequencies. This paper proves the fact, and explains and verifies the proposed method with simple examples.