Nonlinear noise reduction of auscultation signal analysis in Traditional Chinese Medicine

The auscultation diagnosis of TCM means to use the correspondence of five kinds of sounds to find out the lesion in the five internal organs. The signal of the auscultation is always accompanied by noise. Unfortunately, the common filters can only denoise in the linear signals. In this paper, the noise is reduced by the locally projective algorithm in the nonlinear signals. Using Grassberger-Procaccia algorithm to calculate correlation dimension, the correlation dimension of the signal after the denoise is lower than that of original signal. The results show that the method well reproduces the nonlinear characteristics of the corrupted signal. The accuracy and reliability of the signal could be improved in TCM signal analysis by nonlinear denoise.