对语音信号的一幀信号（1024点）进行DCT 对正弦信号进行DCT,对比实验图.修改实验代码,设置阈值,绝对值小于阈值的置0,再反变换看波形. -One frame of the speech signal signal (1024) of the sinusoidal signal to DCT DCT, comparative experiments FIG. Modify experimental code, set the threshold value, the absolut