中文摘要：

针对语音增强技术中的信号去噪问题，提出了一种非线性小波自适应阈值去噪方法．该方法采用一个改进的闽值函数，克服了传统软、硬闲值函数的缺陷；在闲值选取规则中，引入尺度相关去噪法而自适应地选取尺度阂值，利用小波系数在空间尺度的相关性进行尺度噪声能量的估计，根据所得尺度噪声能量来选取对应尺度层中的最佳小波系数并作为该尺度的阈值；同时，应用该方法对不同强度噪声背景下的语音信号进行去噪．结果表明，其具有较好的降噪性能．

英文摘要：

A novel scheme of wavelet thresholding for speech signal de noising was proposed. The scheme introduces a new thresholding function to overcome the drawbacks of traditional soft and hard thresholding functions. This newly introduced function is continuous at the threshold, so that it can curb the pseudogibbs phenomena effectively. Besides, it can reduce constant bias between the original wavelet coefficient and the estimated one, which helps to preserve the feature of the signal. With this threshold function, an adaptively selective algorithm of wavelet threshold was then proposed. This algorithm has both the virtues of spatial selective noise filtration method and the traditional threshold de-noising method. It takes advantage of the inter-scale correlations of the wavelet coefficients to estimate the energy of scaled noise signal. In this algorithm, the threshold in each scale is selected based on the scaled noise energy. The simulations demonstrate that the proposed method is superior to some other existing adaptive wavelet de-noising methods.