Simulative Study on the Effect of the Increase of the Sample Rate of a Feedback Active Noise Control System

Active Noise Control Systems are mostly implemented as feedforward control systems which guarantee a noise reduction without a dependency on the delay in the secondary path. To avoid the need of reference sensors feedback control systems can be used. The most widely used reduction algorithm is the Filtered-x Least Mean Squares (FxLMS), which has the disadvantage of being very sensible to delays in the secondary path. Furthermore, the ability to reduce non-stationary broadband noise depends on the frequency with which the system input is updated. This paper presents the results of a simulative study of the variation of the sample rate up to 500 kHz. The simulation is done with a multiple input multiple output model with measured acoustical secondary paths. The noise is a non-stationary broadband white noise. The results show an improvement in noise reduction which is steadily and significantly rising with the sample rate.