Adaptive microphone arrays using FIR and IIR filters

摘要

Conventional adaptive microphone arrays have utilized finite impulse response (FIR) filters. Existing research has suggested the use of infinite impulse response (IIR) filters to obtain improved rejection of interferences. This thesis presents a comparative study of microphone arrays using FIR and IIR filters. The arrays were based on the Frost beamformer and the Griffiths-Jim beamformer structures.;Simulation results verified the significant improvements afforded by IIR filters. It was also shown that the Frost and Griffiths-Jim beamformer structures provided comparable performance.;An experimental 8-element array was implemented and sound measurements were obtained from an anechoic chamber and a lounge room. The anechoic measurements were used to verify the simulation results. Results from the lounge room indicated the benefits of IIR filters were limited by their increased sensitivity to input noise and reverberation. However, microphone arrays using IIR filters were consistently less prone to frequency coloration or attenuation of the desired signal.