Research On Adaptive Echo Cancellation Based On Microphone Arrays

In many hands-free speech communication systems, the speech signals are inevitably interfered by the noises from the environment and the acoustic echo of the rooms. These interferences will not only cause the degradation of speech quality, but also lead to a sharp deterioration performance of the speech communication system. Compared to single microphone systems, a substantial gain in performance is obtainable due to the spatial filtering capability to enhance speech from the desired direction while suppress interfering signals coming from all other directions. A commonly adopted approach to deal with the problem brought by acoustic echoes in speech communication is to apply adaptive echo cancellation, it is essential to improve the speech quality.In many cases, the sound source is located in the near field of microphone array, the sound wavefront is spherical nature. If using the far field beamforming methods to pick up the speech signal from near field, the performance of the speech communication system would be deteriorated sharply. In order to solve this problem, a nearfield compensation method for nearfield beamforming is outlined.This paper study on the adaptive acoustic echo cancellation based on microphone array speech communication system when the sound source is located in the near field of microphone array. To cancel the acoustic echo and avoid the undesirable delay, a closed-loop delayless subband adaptive filter is applied. Simulation based on MATLAB shows that it is effective and works well in acoustic echo cancellation. Compared with full band NLMS algorithm, the method can obtain fast convergence rate and low misadjustment.