Analytical study of different approaches for active control of sound transmission through double walls

Sound transmission through double plate structures into an enclosure and its active attenuation are modeled and analyzed in this paper. Using the modal acoustic transfer impedance and mobility matrices, the excitation and interaction in the double plate sound transmission system can be described with clear physical significance. Three active control arrangements are considered for a double wall sound transmission model. They are: (1) to directly attenuate the room modes by using one acoustic control source in the room; (2) to control the sound radiation into the room using a vibrational actuator on the radiating structure; and (3) to block the noise transmission path by inserting one acoustic control source within double wall partition. The analytical solution of the system response is used to explain the mechanisms of attenuation associated with these three control arrangements. The effectiveness and performance of the control system corresponding to each arrangement are discussed.