一、声波的多普勒效应在日常生活中 ,我们都会有这种经验 :当一列鸣着汽笛的火车经过某观察者时 ,他会发现火车汽笛的声调由高变低 .为什么会发生这种现象呢 ?这是因为声调的高低是由声波振动频率的不同决定的 ,如果频率高 ,声调听起来就高 ;反之声调听起来就低 .这种现象称为 First, the Doppler effect of sound waves In everyday life, we all have this kind of experience: When a train whispering a whistle passes by an observer, he will find that the tone of the train whistle will change from high to low. Why does this occur? Phenomenon? This is because the level of the tone is determined by the frequency of the sound wave vibrations. If the frequency is high, the tone sounds high; otherwise, the tone sounds low. This phenomenon is called