The application of heart sound denoising using local projection and discrete wavelet transform
LIANG qingzhen , GUO xingming,YUAN zhihui
College of Bioengineering, Chongqing University , Key Laboratory of Biorheological Science and Technology , Ministry of Education , Chongqing 400044 , China
Abstract:For the nonlinear characteristics of heart sound signal, a heart sound denoising algorithm which use local projection based on adaptive estimation of noise level combine with discrete wavelet threshold was proposed, it can reconstruct signal accurately and can retain the effective characteristics of weak signal. Numerical simulation results of the Lorenz sequence show that the method can effectively filter out the noise, the signal to noise ratio and mean square error are superior to the local projective or discrete wavelet threshold denoising method. Compared to the Largest Lyapunov index of the signal before and after denoising between different algorithms, it concluded that the method can filter out noise at the same time can better retain the characteristics of the original signal. The denoising research of actual measured heart sound further shows the effectiveness of this method.