我们对中学物理中有关声音的音调、响度和共振的演示实验做了一些改进，使实验现象更加直观、明显，而且增加了趣味性，获得了良好的效果， 为了增强实验的可信度，我们研制了一台“声音频率显示仪”，其电路方框图如图１所示．由驻极体话筒拾音，信号经两级三极管放大器放大后 We have made some improvements to the demonstration experiments on pitch, loudness, and resonance of sounds in the middle school physics, which made the experimental phenomena more intuitive and obvious, increased the interest, and achieved good results. In order to enhance the credibility of the experiments, we Developed a “sound frequency display instrument”, the circuit block diagram shown in Figure 1. Electret microphone pick up, signal amplified by two-stage transistor amplifier