This exhibit lets you adjust the speed of sound, the speed of the speaker, and the frequency of the sound. This let's you see why the train whistle changes pitch as it passes you, and the sonic boom which is caused when objects move faster than the speed of sound. You can drag the ruler around to measure the distance between wavecrests.
This was created by Raman Pfaff. Shockwave is being phased out as it is no longer supported in modern browsers.