说明：  给原始语音加已知信噪比的高斯白噪声，随着信噪比不断变大，找出大概能使原始语音的波形特征不明显的信噪比范围。
(Known to the original speech plus noise ratio of Gaussian white noise, with the signal to noise ratio becomes larger and larger, to find out about the original speech waveform characteristics to make the obvious range of SNR.)