A New Self-calibration Technique for Adaptive Microphone Arrays

A simple channel calibration for microphone arrays is proposed. A gain is applied to the signal in each channel. The signal power in each channel is normalized by its time-averaged power and scaled by the channel-averaged power. This allows equalization of the gains without any change in the output power of the fixed beamformer. Suppressing the gain difference reduces directivity distortion and avoids target speech cancellation by the microphone array. Evaluation results in a simulated environment demonstrate that the gain difference as much as 3.1dB is suppressed. This calibration is robust to an interference direction of arrival (DOA) of up to 90◦. The improvement in the target speech leakage through a fixed blocking matrix is also shown. Experimental results in the real environment with DOAs of 30◦ to 90◦ and signal-to-interference ratios of 0dB and 10dB show that the proposed method reduces the gain difference by 80% of the initial 1.26dB difference.