One-dimensional near field speaker based on the sound radiation characteristics of a flexible beam

Abstract

This paper concerns a methodology of generating a localized sound field using a one-dimensional speaker array. Although directional loudspeaker such as a parametric loudspeaker generates a sound beam only for the specific direction, such a method leaks sound to outside of the specific area due to reflection of the sound wave. In order to cope with this problem, a generation method of localized sound field at a single frequency was proposed which is based on the phenomena that radiated sound from vibration of a flexible structure under the specific conditions decays drastically more than normal distance decay effect. The objective of this paper is to expand this methodology for the multi-tone case. First, fundamental theory of a flexible beam is confirmed. Next, it is clarified that the sound filed generated by a flexible beam can be localized under specific conditions. This is followed by the generation of a localized sound field using speaker array and its expansion to the multi-tone case. Finally, some numerical simulations are carried out, clarifying the validity of the proposed method.