An Active Noise Cancelling System for Moving Noise Source

摘要

Recently many researches about multi-input multi-output (MIMO) active noise cancelling (ANC) system have been conducted towards practical application. In this paper, we present an ANC system for moving noise source. In our study, the MIMO ANC system structure is described by state space equation. In order to deal with the varying characteristic of primary acoustic propagation path, we divide time signal into block data sequentially, and for each block, we estimate the system of primary path by using subspace identification method. Also to eliminate the effect of secondary acoustic propagation path, we connect an inverse system of the secondary path to the estimated primary path. Eventually we can obtain the control sources for noise cancellation at each cancelling point. According to this proposed method, a computer numerical simulation is carried out using a measured 4-channel helicopter noise data set. As a result, the 4-channel noise power can be improved about -20db on average, this shows that our proposed method works effectively.