Low frequency noise control in duct based on locally resonant membrane with attached resonators

In this paper, locally resonant membrane with attached resonators is introduced to duct system to achieve good noise control effect especially in low frequency range. A rigorous analytical model based on modal expansion method is developed to investigate the vibroacoustic coupling characteristic of proposed duct-membrane-resonator system. The corresponding theoretical results show a good agreement with numerical simulation. The velocity distribution, sound transmission loss curve, and the mechanism behind are discussed and explained deeply. It is found that the attached resonators on the membrane can lead to new transmission loss peak which is related to but not exactly equal to the resonance frequency of attached resonator itself. Correspondence between zero equivalent density mass and transmission loss peak is achieved at the non-antisymmetric modes. Compared to single resonator, multi-resonators system can realize more transmission loss peaks for better sound transmission effect. In principle, ultra-low frequency noise reduction and arbitrarily adjustable frequency can be achieved by changing the frequency, position, and number of exerted resonators, which provide a new approach for duct noise control.