Evaluation on flexible beamformers with curved-type parametric loudspeaker for spatial audible area design

In the fields such as evacuation guidance and entertainment, it is important for each listener to provide different sound information by using some loudspeakers in a same room. However, listeners have difficulty obtaining target sound information because various sound signals are mixed by using a general loudspeaker which has a wide directivity. To solve this problem, a parametric loudspeaker which has a high directivity by utilizing an ultrasound wave is ideal candidate. The parametric loudspeaker can provide each listener the target sound information because it can form the spatial audible area to the narrow space. However, the conventional parametric loudspeaker system requires a large system using too many parametric loudspeakers corresponding to each listener. In this paper, we therefore propose flexible beamformers with curved-type parametric loudspeaker for spatial audible area design using a small system. The proposed method utilizes the curved surface arrangement of ultrasound transducers and can design various spatial audible areas by changing its curvature. Finally, we evaluated the relationship between its curvature and spatial audible area in the proposed method. As a result of the evaluation experiment, we confirmed the effectiveness of the proposed method.