Study on Sound Generating Mechanism Using Vibrational Energy and Sound Energy. 2nd Report. Relationship between Structural Intensity Vortex Flow and Sound Field.

Abstract

Most of the sound generated by vibrating structures is structure-borne sound. The purpose of this study is to investigate the generating mechanism of the structure-borne sound using vibrational energy and sound energy. The analytical model is a rectangular plate which is one of the basic elements of structures. The plate is excited sinusoidally at one point on the plate and proportional damping is taken into consideration. The dynamic response of the plate is calculated using the finite element method to obtain vibrational energy and sound energy. This paper describes the relationship between sound energy generated by a vibrating plate and vibrational energy flow patterns at different excitation points. As a result, sound radiation efficiency varies under the condition that generates the vortex flow patterns of the vibrational energy, while it is constant under other conditions. Sound energy under the influence of the vibrational energy flow can be estimated from sound radiation efficiency and two kinds of energy ratios. The influence of the vibrational energy flow patterns on sound field can be expressed by the phase distribution of complex displacement on the vibrating plate.