Abstract : During the past decade, the Wavelet Transforms (WT) have been applied to various research areas. Their applications include signal and image denoising, compression, detection, and pattern recognition. To our knowledge, denoising methods based on the wavelet thresholding have not been successfully applied to speech enhancement. However, wavelet transform combined with other signal processing tools has been proposed. In this paper, we pass in review the principal wavelet denoising methods published in the literature. Then, we expose the speech enhancement techniques using wavelet
transform. Next, we point out the difficulties encountered in the wavelet thresholding methods and finely we propose some solutions.