因为傅立叶变换对应的是无限信号,信号经过分帧后变成有限信号,分帧的信号再进行傅立叶变换后,高频部分将有 泄露 ,所以要加窗.

窗函数的拼谱都是在某高频部分截止,所以每帧信号加窗后的傅立叶变化,频谱基本 泄露 -Because Fourier transform corresponding is infinite signals, signals after framing become limited, framing signal again after Fourier transform, the high frequency part will have　leaked , so to add window.

Window function spell spectrum are in a high frequency part of the globe, so each frame and window after Fourier transform, signal spectrum basic　leak