Some physical insights for active acoustic structure

Active acoustic structure (AAS) proposed in recent years has been viewed as an encouraging approach to actively control sound radiation from vibrating structures. Much work of AAS has been done on theoretical model, arrangement of the secondary panel and error sensing, and experimental investigation of AAS system, but physical mechanisms is little understanding. In this study, under minimization of the total sound power output, the physical mechanism of noise reduction is investigated by analyzing the sound power output change of primary and secondary structures and the distribution of sound intensity. The results show that there are two kinds of energetic behaviors, which includes the suppression of the sound power radiated by the primary panel and absorption of sound power by the primary and secondary panels.