A noise reduction system in arbitrary noise environments and its applications to speech enhancement and speech recognition

The paper proposes a novel noise reduction system in arbitrary noise environments, consisting of localized and nonlocalized noises, where few existing systems work well. In the proposed system, localized noises are estimated and reduced by the hybrid noise estimation technique we previously proposed and spectral subtraction. Non-localized noises are reduced by a post-filter whose performance is further improved by a novel estimator for the a priori speech absence probability calculated under the assumption of a diffuse noise field. Experimental results show that the proposed system results in significant improvements in terms of speech quality measures and speech recognition performance in various noise conditions.