Cavity Control and Panel Control Strategies in Double-Panel Structures for Transmitted Noise Reduction

Investigation and comparisons of the cavity control and the panel control in a double-panel structure are presented in this paper. The double-panel structure, which comprises two panels with air in the gap, provides the advantages of low sound-transmission at high frequency, low heat-transmission and low weight. Therefore, the double-panel structure is adopted in various applications such as aerospace and vehicle industry. However, the resonance of the air cavity and the high sound-transmission at low frequency limit its noise control performance. Furthermore, the resonant behaviors and the sound radiating modes of single panel structures are different from double-panel structures. As a consequence, the panel control strategy, which is widely applied in structural acoustic control, for single-panel structures needs to adapt to double-panel structures. In this paper, a structural-acoustic coupled model is developed to investigate and to compare various panel control and cavity control methods. A detailed investigation of the structure and the cavity resonance is shown. Both the numerical analysis and the real time control results show that the panel control should apply to these two panels simultaneously. Cavity control by loudspeakers modified to operate as pressure sources can provide remarkable noise reduction in the double-panel structures. Finally, the combination of feedforward panel control and feedback cavity control can further reduce the transmitted noise.