Design of Neural Directional Gain Post-filtering for Microphone Array Beamforming
摘要
Microphone array beamforming is a fundamental technique for speech enhancement. A practical implementation method for microphone array beamforming involves splitting the beamforming filters into two sequential components: first a fixed beamformer, followed by a post-filter gain. Conventional post-filtering methods rely on single-channel noise reduction, assuming that residual noise and target speech are uncorrelated. However, these methods often face challenges in suppressing residual interference, as they lack spatial selectivity and may inadvertently amplify interfering signals. To address this limitation, this paper proposes a neural direction-gain for post-filtering, which is cascaded with a robust superdirective beamformer to enhance directivity and speech quality. The core of the proposed method is a direction-aware post-filter network, in which a mask decoder dynamically estimates the directional gain, while a complex decoder adaptively refines the real and imaginary components of the output signal. This architecture enables joint optimization with the superdirective beamformer, resulting in enhanced interference suppression and improved perceptual quality.