Abstract
Theoretical investigations are made on the sound radiation from a system consisting of a vibrating wall and a layer of porous material mounted on the wall. The wall has an arbitrary amplitude distribution and the material is in the same motion as the wall. The radiation field is obtained from the solution of a boundary value problem in the whole space including the inside of the material and free space in which the sound is radiated. The “generalized efficiency coefficient of radiation” is proposed. By using it, simple formulas for the radiation pattern and the radiation power are obtained.
