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http://dx.doi.org/10.7776/ASK.2006.25.8.383

A Novel Approach to a Robust A Priori SNR Estimator in Speech Enhancement  

Park, Yun-Sik (인하대학교 전자전기공학부)
Chang, Joon-Hyuk (인하대학교 전자전기공학부)
Publication Information
The Journal of the Acoustical Society of Korea / v.25, no.8, 2006 , pp. 383-388 More about this Journal
Abstract
This Paper presents a novel approach to single channel microphone speech enhancement in noisy environments. Widely used noise reduction techniques based on the spectral subtraction are generally expressed as a spectral gam depending on the signal-to-noise ratio (SNR). The well-known decision-directed(DD) estimator of Ephraim and Malah efficiently reduces musical noise under the background noise conditions, but generates the delay of the a prioiri SNR because the DD weights the speech spectrum component of the Previous frame in the speech signal. Therefore, the noise suppression gain which is affected by the delay of the a priori SNR, which is estimated by the DD matches the previous frame rather than the current one, so after noise suppression. this degrades the noise reduction performance during speech transient periods. We propose a computationally simple but effective speech enhancement technique based on the sigmoid type function for the weight Parameter of the DD. The proposed approach solves the delay problem about the main parameter, the a priori SNR of the DD while maintaining the benefits of the DD. Performances of the proposed enhancement algorithm are evaluated by ITU-T p.862 Perceptual Evaluation of Speech duality (PESQ). the Mean Opinion Score (MOS) and the speech spectrogram under various noise environments and yields better results compared with the fixed weight parameter of the DD.
Keywords
a Priori SNR; Decision-Directed; Speech Enhancement; Sigmoid Type;
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