关键词: 小波去噪, 阈值函数, 清浊音分离

Abstract: An optimal speech denoising method which combines wavelet shrinkage and separation of unvoiced sounds and voiced sounds is presented.Firstly，the unvoiced sounds in speech often contain many high-frequency noise-similar components.If wavelet shrinkage method is directly adopted，it is likely to remove mistakenly these high-frequency components and result in distortion of speech，so it is necessary to separate unvoiced sounds and voiced sounds.Secondly，the optimal method of wavelet shrinkage is followed by optimization of many aspects such as different wavelets，threshold selection rules and threshold functions.Compared with the traditional method，it either removes noise as much as possible or retains the original characteristics of speech，which improves speech quality greatly.

Key words: wavelet denoising, threshold function, separation of unvoiced sounds and voiced sounds