Active noise control system using motional feedback loudspeaker

Abstract

The active noise control system using motional feedback (MFB) loudspeaker is proposed which is effective in the low frequency range. Although FIR digital filter is used for usual control system, it is difficult to realize ideal MFB type active control system because the group delay in FIR filter affects the phase characteristics. In this paper, we realize the IIR filter using DSP with high speed A/D and D/A convertors to reduce the group delay. The positive insertion loss is obtained from 21 to 94Hz on the model experiment. However, the obtained insertion loss is lower than one obtained in numerical simulation because of an oscillation about 300Hz.