Everyone knows the characteristic sound of raindrops falling in a puddle. But what produces this sound?

During our laboratory course on fluid physics we tried to find out what causes this sound by studying the impact of a water droplet on a liquid water surface. This resulted in beautiful images:

According to theory, there are several factors concerning the falling droplet that produce waves and thus sound. A brief summary of our efforts on creating reliable ‘laboratory rainfall conditions’ can be found in the section process. Limitations on our used setup are also discussed in detail in the section setup. Furthermore, our results give rise to an interesting analysis and discussion.