Noisy-pretreatment

代码说明：

  纯语音和带噪语音,信噪比,带噪语音的产生,语音信号的预处理一——消除趋势项和直流分量(Pretreatment with a pure voice and noisy speech signal to noise ratio, resulting in noisy speech, the speech signal- to eliminate the trend term and DC components)