Speech enhancement based on modified a priori SNR estimation

Abstract

To solve the frame delay problem and match the previous frame, Plapous et al. [IEEE Transactions on Audio, Speech, and Language Processing, 2006, 14(6): 2098–2108] introduced a novel approach called two-step noise reduction (TSNR) technique to improve the performance of the speech enhancement system. However, TSNR approach results in spectral peaks of short duration and the broken spectral outlier, which degrade the spectral characteristics of the speech. To solve this problem, a cepstral smoothing step is added in order to remove these spectral peaks brought by TSNR approach. Theory analysis shows that the proposed approach can effectively smooth the spectral peaks and keep the spectral outlier so as to protect the speech characteristics. Experiment results also show that the proposed approach can bring significant improvement compared to decision-directed (DD) and TSNR approaches, especially in non-stationary noisy environments.

Key words： speech enhancement; decision-directed (DD); two-step noise reduction (TSNR); signal-to-noise ratio (SNR) estimation

Acknowledgements

This work was partially supported by the National Natural Science Foundation of China (Grant Nos. 61005004, 61175011, and 61171193), the Next-Generation Broadband Wireless Mobile Communications Network Technology Key Project (No. 2011ZX03002-005-01), the 111 project (No. B08004), and Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry.

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