ANALYSIS AND MEASUREMENT OF SOUND TRANSMISSION THROUGH A DOUBLE-WALLED CYLINDRICAL SHELL

Sound transmission through a double-walled cylindrical shell is studied. The solution that describes the system response is obtained by combining the solutions of two different models of the system. The first model, which describes the sound transmission due to the interaction between the acoustic waves and the bending waves in the shells, is formulated by three acoustic wave equations and two shell vibration equations. The second model describes the sound transmission by one-dimensional waves propagating through the layers of the shells and the air-gap. The transmission losses calculated from the two models are combined to represent the system response in the entire frequency range. Analytical solutions are compared to corresponding measured results, which shows reasonable agreements if the extent of the simplifications used in the analytical model is considered. The effects of important design parameters such as the air-gap size and the thickness ratio are studied using analytical solutions.