Celse K. Amedin
G. A. U. S., Dept. of Mech. Eng., Univ. de Sherbrooke, Sherbrooke, Quebec J1K 2R1, Canada
A new method is suggested for the characterization of porous materials; it is based on a measurement of the sound transmission through a layer of the material. This paper presents two theoretical models to evaluate the potential of the method. In these models, a thin layer of the material lies on a horizontal baffle; the acoustic source is a waveguide mounted vertically under the baffle with its end flush to the baffle and the sound is transmitted through the layer to the half-space above the layer. The two models calculate the transfer function between the volume velocity of the waveguide and the sound pressure over the layer. The first model is based on the integral method and collocation in which the appropriate Green's functions are used to describe the sound field. The second model uses a method of decomposition into plane waves. The details of each model are described; results, comparisons, and validations are presented. Finally, the potential of the method to evaluate the characteristics of the porous layer is discussed.