说明：  这是标准谱减算法和小波阈值降噪方法，虽然效果不太好，但是作为经典降噪方法，还是有很高的参考价值，也是此类文献引用最多的方法。
(This is the standard spectral subtraction and wavelet thresholding method of noise reduction, although results are not good, But as a classic noise, or a high reference value, such literature is the most used method.)