Modified GSC Method to Reduce the Distortion of the Enhanced Speech Signal Using Cross-Correlation and Sidelobe Neutralization

Hang Su,Chang-Myung Lee

doi:10.3390/app11146288

Abstract

The generalized sidelobe canceller (GSC) method is a common algorithm to enhance audio signals using a microphone array. Distortion of the enhanced audio signal consists of two parts: the residual acoustic noise and the distortion of the desired audio signal, which means that the desired audio signal is damaged. This paper proposes a modified GSC method to reduce both kinds of distortion when the desired audio signal is a non-stationary speech signal. First, the cross-correlation coefficient between the canceling signal and the error signal of the least mean square (LMS) algorithm was added to the adaptive process of the GSC method to reduce the distortion of the enhanced signal while the energy of the desired signal frame was increased suddenly. The sidelobe pattern of beamforming was then presented to estimate the noise signal in the beamforming output signal of the GSC method. The noise component of the beamforming output signal was decreased by subtracting the estimated noise signal to improve the denoising performance of the GSC method. Finally, the GSC-SN-MCC method was proposed by merging the above two methods. The experiment was performed in an anechoic chamber to validate the proposed method in various SNR conditions. Furthermore, the simulated calculation with inaccurate noise directions was conducted based on the experiment data to inspect the robustness of the proposed method to the error of the estimated noise direction. The experiment data and calculation results indicated that the proposed method could reduce the distortion effectively under various SNR conditions and would not cause more distortion if the estimated noise direction is far from the actual noise direction.

Highlights

Online meetings are widely used in the current time
2d.4e.siTrehde sPirgonpaols. eTdhGe SsiCde-SloNb-eMneCuCtraMlieztahtoiodn method was placed in the primary path of the the generalized sidelobe canceller (GSC)-sidelobe neutralization (SN)-MCC method was proposed by combining the GSC-MCC method and the GSC-SN method to improve the performance of the GSC method
This paper proposed a modified GSC method to reduce the distortion of the enhanced signal using cross-correlation and sidelobe neutralization

Summary

Introduction

Online meetings are widely used in the current time. The quality of meeting audio has become increasingly important. Some studies [21,22,23] introduced post-filtering methods to the microphone array for additional noise reduction to the beamforming output signal. The step size of the adaptive algorithm in the GSC method was controlled by the cross-correlation coefficient between the cancelling signal and the error signal to reduce the distortion that occurred by the change of the speech energy. Based on the excess mean-square error (MSE) of the LMS algorithm [30,31] and the theoretical limits of the noise reduction performance [32], the sidelobe neutralization (SN) method was presented to reduce the noise component in the beamforming output signal of the GSC method to improve the denoising performance. The beamforming pattern could be approximated as a zero-order Bessel function

Beamforming Sidelobe Neutralization

Effect of the Inaccurate Estimated Noise Direction

Findings

Conclusions