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代码说明：

  绘制电脑中原始人声信号的时域、频域图，并在其上加入高斯白噪声，之后设计巴特沃兹滤波器将其滤除。(The draw primitive people in the computer sound signal time domain, frequency domain, and join in on the white Gaussian noise, after design Butterworth filter to filter out.)