Projection of a virtual speaker into a vehicle using sound field control

Abstract

In this study, we propose a system which projects a virtual speaker into a vehicle by controlling the sound field of the interior of the vehicle. The system uses a sound field reproduction technique to reproduce a point source in the vehicle representing a virtual speaker, enabling drivers to communicate with virtual speakers as if they were riding in the same vehicle. The system is based on a sound field reproduction technique known as Wave Field Synthesis (WFS), which can represent the depth of a sound source by reproducing its wavefront precisely. However, since WFS is generally implemented in an ideal environment, the influences of reflection and reverberation are not generally taken into consideration. Therefore, in order to apply WFS to an in-vehicle system, it is necessary to investigate the effects of reflection and reverberation on WFS within a vehicle. To do so, we compare the accuracy of the perception of locations of sound point sources reproduced using WFS with a 32 channel loudspeaker array in both a vehicle and a low reverberation room. We also compare perception accuracy of the proposed system with perception accuracy when a loudspeaker is placed in the same position as the virtual speaker.