Adaptive active broadband absorption pipeline system design

Passive acoustic material is effective for the control of high frequency noise, but not for low frequency. In order to broaden the absorption band of passive material, an active/passive hybrid absorption control method is proposed in this paper in which the corresponding model is developed and the mechanism is clarified. By real time signal processing system established in the standing wave tubes of both air and underwater, the test result shows that the proposed method could control the signal noise of single frequency signal, pulse signal, sweep signal and broadband white noise, it could improve sound absorption performance of the passive material in frequency range from 400Hz to 1800Hz.