Commercial aircraft cabin noise reduction based on SEA and transfer-matrix method

A computational acoustic model has been prepared to estimate the cabin noise of a commercial aircraft with a tail suspension engine based on SEA method. The main noise sources such as engine and TBL have been calculated and the primary transfer path of the aircraft fuselage has been analyzed. After that, a transfer-matrix method is applied to calculate the transmission loss of the panel structures, and to evaluate effectively and rapidly the acoustic insulation of the multilayer structure combined by the skin panel, blankets and trim panel. The results display that the sound level in the rear of the aircraft exceeds the passenger cabin acoustical comfortable requirement. A series of noise treatments should be considered to the panels which are the main transfer path of external noise into the cabin. Meanwhile, an optimal approach should be applied to the aircraft and validated by flight test. The results show that (1) the ceiling panel of cockpit is the main transfer path of TBL excitation into the cabin, while the window side panel and trim panel located at the rear of the fuselage are the main transfer path of the engine noise into the cabin; (2) the sound insulation performance of the side wall panel would be improved by increasing the density and thickness of the blanket and adding the damping layers on it; and (3) the cabin noise level would be reduced about 3 dB when the optimal panel configuration is applied to the aircraft with the penalty of adding weight about 45 kg. (c) 2018 Institute of Noise Control Engineering.