Research On Differential Microphone Array Based Active Noise Control System

In active noise control(ANC)systems,omni-directional microphones are often used to provide signals for the controller.Due to the omni-directivity of the microphones,some unwanted signals can be picked up by the microphones,which interference the performance of the ANC system.For the feedback ANC system that relies on error signal,if interference sound waves in space are picked up by the error microphone,the system may fail to work.To solve the above problem,this thesis researches on the differential microphone array(DMA)based ANC system.In the proposed differential error feedback ANC system,the error signal is provided by the DMA.In such a way,the interference is mitigated.However,when the error signal is provided by the DMA,the location of the DMA does not indicate the control point of the ANC system.An auxiliary filter based mapping method is proposed to solve the problem of the control point.Simulation results show that differential error feedback ANC system is more robust against interference than conventional feedback ANC system,and the auxiliary filter based mapping method can improve the noise reduction performance of the differential error feedback ANC system.When the computation related to DMA is introduced into a ANC system,the computational load of the local controller will increase.For ANC systems,the introduction of wireless communication and separation of computation tasks to the cloud can reduce the computational load of the local controller.Thus,this thesis researches on the wireless networked adaptive online modeling ANC.A digital twin online secondary path modeling(DT-OSPM)algorithm that can model the secondary path online is proposed.In this algorithm,the generation of anti-noise and the adaptation of control filter are executed by the local controller and the cloud respectively,thereby the computational loads of adaptation on the local controller are saved.Simulation and experiment results show that the DT-OSPM algorithm can achieve noise control and secondary path modeling,and cope with the changes in the primary noise and the secondary path during the control.