バフル中の膜の音響 : 振動連成数値解析 Numerical vibro-acoustic analysis of sound fields coupled with a baffled membrane

In order to predict sound fields, particularly in the presence of membranes of arbitrary shape, the present paper introduces a method of numerical analysis that couples acoustic systems to membrane vibration systems, while taking into account membrane permeability. To be concrete, the finite element method is applied to membrane vibration systems, the boundary integral equation method is applied to acoustic systems, and these two systems are coupled in a procedure introducing specific flow resistance of membranes. This method is validated through its application to a two-dimensional problem in which a plane wave is incident upon a membrane stretched in a finite rigid baffle. The results are compared with those obtained by the mode expansion method and good agreement is shown. Subsequently, the effects of membrane properties, such as surface density, tension and flow resistance, on the surrounding sound fields and the acoustic characteristics of the finite membrane are discussed in detail.