Spectral combining for microphone diversity systems

In telecommunications, diversity combining for multiple receiving antennas is a commonly used technique to achieve robustness for fading channels. This paper proposes a frequency domain diversity approach for two or more microphone signals, e.g. for in-car applications. The microphones should be positioned separately to insure diverse signal conditions. This enables a better compromise for the microphone position with respect to different speaker sizes and noise sources. The microphone signals are weighted with respect to their signal-to-noise ratio and then summed similar to maximum-ratio-combining. The output SNR is significantly improved compared to single microphone noise reduction systems, even if one microphone is heavily corrupted by noise.