关键词: 语音增强, 小波变换, 阈值去噪, μ律拟合, 自适应阈值

Abstract: Aiming at wavelet threshold denoising，for the issue of signal being sensitive oscillation after the treatment of hard-threshold functions and the issue of signal? being over-distortion after the treatment of soft-threshold functions，a new threshold function based on μ law fitting is put forward.According to the different singularities between speech signals and noises for the different wavelet scales，in another words，based on the facts that modulus of wavelet transform coefficients of speech signals increases while the wavelet transform coefficients of noises decreases by the increasing of wavelet scales，an adaptive thresholds is put forward.It is proved by experiment that definition and intelligibility of voice are obviously increased by enhancing of this new calculation method.

Key words: speech enhancement, wavelet transform, threshold de-noising, μ law fit, adaptive thresholding