说明：  求离散傅立叶频谱, 重构低通滤波,在噪声环境下语音信号的增强,语音信号为读入的声音文件,噪声为正态随机噪声
(Discrete Fourier spectrum seeking to reconstruct low-pass filter, the noise enhancement of speech signals, speech signal is read into the sound file, the noise is normal random noise)