Research on Sound Directivity of Traffic Signal by Using Flat Speaker

Abstract

In recent years, demand for acoustic signals has increased as a barrier-free equipment for the visually impaired people. However, a guide sound is a noise to neighbors, and a penetration rate of acoustic signals is very low. The purpose of this study is to develop a directional speaker by using piezoelectric vibrator. In the experiment, the rectangular flat panel speaker was produced experimentally, which is centrally excited by piezoelectric vibrator. In order to clarify to the directional mechanism, the visualization measurements using the spatial transfer function was evaluated. As a result, the prototype speaker had narrow directivity and generated the plane wave at a specific frequency. Furthermore, the formation of plane wave was affected by the near field of flat panel, in where three strongly sound radiations were observed.