观测实时模拟信号（语音）的频谱 用音频设备采集一段语音，将语音存为.wav格式。对wav文件作分段傅里叶变换分析。语音是分音节的，应把它分段分析，而且实际运用中的数字信号处理的FFT的点数是有限的，一般只能达到千点。用傅里叶反变换IFFT，从频域恢复信号。画出频谱图和语音波形图。 -Observing real-time analog signal (voice) of the spectrum collected with the audio devices section of

把语音芯片ISD1420录放音时间20秒分成20段，每段一秒，调用录音子程序，录入语音，建立语音库，语音录入结束后，根据段地址，调用放音子程序，还原原来录入语音信号。- The voice chip ISD1420 sound recording time of 20 seconds is divided into 20 segments, each second, a subroutine call recording, voice input, speech database estab

提取淹没在噪声中的周期信号要求自相关（以判断周期）和互相关（以恢复信号自身）-Extraction drowned in the noise requirements of a periodic signal autocorrelation (to determine the cycle) and cross-correlation (to restore the signal itself)