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

Recently, active noise control technology has been used to increase the sound transmission loss of double-wall structures. Several approaches have been put forward and explored individually. However, no comparative study on those approaches has been conducted to show which approach is more effective for given circumstances. In this paper, three different approaches for controlling sound transmission through double-panel partitions into a room, i.e., applying acoustic control sources in the air gap between the two panels (cavity control), applying vibration control sources on the radiating panel (panel control), and applying acoustic control sources in the receiving room (room control), are studied and compared to each other experimentally. The mechanisms involved in each approach are illustrated and the conditions for effective noise attenuation are examined. The results show that the modal overlap of each subsystem (the cavity, the radiating panel, and the room) and the control mechanisms involved are the two most important factors that determine the effectiveness of each corresponding approach. (C) 1997 Acoustical Society of America.