Robust sound image localization for moving listener with curved-type parametric loudspeaker

Recently, technologies for reproducing a 3-D sound field are required for providing highly realistic sensations. We previously proposed a system with multiple parametric loudspeakers that have a higher directivity by using ultrasound to reproduce an audible sound in a particular area. These loudspeakers can design sound images on walls, ceilings, and floors by reflecting an emitted sound, and thus, the proposed system can easily present incoming sound from various directions. However, it is difficult to maintain the performance of sound image localization when a listener moves away from the reproduction area of the emitted sound. In this paper, we propose a sound image design method with robust localization for moving listeners. In order to constantly present the sound image localization, the method needs to steer the direction of emission in accordance with the movement of the listener. To enable this, we developed a curved-type parametric loudspeaker consisting of ultrasonic transducers arranged in an arc. The proposed method can steer the emitting direction by switching the input ultrasonic transducers without moving itself. Experimental results clearly demonstrate the effectiveness of the proposed method.