Transmission of reverberant sound through single walls

The transmission of reverberant sound through homogeneous single walls has been investigated theoretically and experimentally.Random incidence sound-transmission meas urements were made on homogeneous walls of aluminum, plywood, and plasterboard.The results were found to be in satisfactory agreement with a modified version of a theoretical treatment first given by Cremer, which postulates that the wall impedance has a resistive component in addition to its mass reactance and a stiffness reactance res ulting from the occurrence of flexural waves.Two of three parameters that are r equired to predict the transmission loss, namely, resistance, and critical flexure frequency, the third one being mass, are evaluated from the experimental data in such a way as to obtain the best fit between the theoretical and exp erimental results.Conditions under which the mass law of so und transmission may be ass umed to be valid are investigated in detail by studying the behavior of Rayleigh's transmission law, which takes into account the compressional waves induced in the wall.Experimentally, it was found that considerable improvement in transmission loss could be obtained by applying a fairly substantial sound-absorbent blanket to one of the faces of a homogeneous wall.