Abstract
The present study aims to analyze the noise reduction from double membranes with an air cavity between them in a rigid duct for the determination of acoustic radiation and transmission losses. A mode-matching scheme for solving the governing boundary value problem is presented. The proposed scheme is also suitable for taking into account the contribution of the higher order mode and for imposing physical conditions at the membrane edges. The correctness of the truncated mode matching solution is verified by checking the conservation laws and reformulating the normal velocities at the interfaces. Numerical experiments show that the stiffness of the elastic components and the geometric configuration of the device significantly affect the attenuation of the propagating modes.