们知道，声音的频谱范围约在几十到几千赫兹，若能利用程序来控制单处机某个口线的“高”电平或低电平，则在该口线上就能产生一定频率的矩形波，接上喇叭就能发出一定频率的声音，若再利用延时程序控制“高”“低”电平的持续时间，就能改变输出频率，从而改变音-We know that the sound spectrum in the range of tens to thousands of cycles per second, if we use program to control an exit line single office machine " high"　level or low level, then in the mouth can produce a certain line frequency square wave, connected to the speaker' s voice can be given a certain frequency, if more delay programmed using " high"　" low"　level the duration of the output frequency can be changed, thus changing the tone