关键词: 小波变换, 阈值去噪, 阈值函数, 自适应阈值, 最优小波基

Abstract: To overcome the disadvantage in traditional wavelet threshold de-noising approach, the hard threshold function is discontinuous while the soft threshold function has fixed deviation; a new threshold function is proposed. An adaptive threshold is proposed to enhance the fixed threshold put forward by Donoho. Under the Matlab environment, three experiments are separately carried to select the optimum wavelet base, the optimum parameters of the new threshold function and to compare the new threshold function with traditional threshold functions such as the hard threshold function, the soft threshold function and the compromise threshold function. Experimental result shows that the new threshold function is more effective to enhance the Signal-to-Noise Ratio and to improve the quality of the de-noised speech signal.

Key words: wavelet transform, threshold de-noising, threshold function, adaptive threshold, optimum wavelet base