对原时域信号x进行fft，得到频域信号y 频域滤波 对原信号频域滤波，得到滤波之后的频域信号y1（原频域信号y*滤波器c） 求包络谱(The original time domain signal x is FFT, and the frequency domain signal Y is obtained spectrum shaping In the frequency domain filtering of the original signal, the frequency d