新阈值小波变换的心音去噪

Heart sound denoising of new threshold wavelet transform

为有效去除心音信号中夹杂的噪音,提出一种基于离散小波变换(DWT)的心音自适应阈值去噪方法。选取db6小波对心音信号进行5层分解,保留有用的分解层系数进行阈值化处理和信号重构,并将其余层的系数设置为零。提出一种新的自适应阈值估计法和阈值函数,引入参数m反映信号中的噪声水平,根据其自适应估计阈值。在不同类型噪声的不同噪声强度下将软、硬阈值函数和新阈值函数对心音信号进行仿真对比。实验结果表明,所提方法去噪效果最好,验证了其有效性和可行性。

To effectively remove the noise in the heart sound signal,a heart sound adaptive threshold denoising method based on discrete wavelet transform(DWT)was proposed.The db6 wavelet was selected to perform 5-layer decomposition on the heart sound signal,and the useful decomposition layer coefficients were reserved for thresholding processing and signal reconstructing,and the coefficients of the remaining layers were set to zero.A new adaptive threshold estimation method and threshold function were proposed.The parameter m was introduced to reflect the noise level in the signal,and the threshold was estimated based on its adaptation.The soft and hard threshold functions and the new threshold function were simulated and compared with the heart sound signals under different noise intensities of different types of noise.Experimental results show that the proposed method has the best denoising effect,and the effectiveness and feasibility of the proposed method are verified.