Results

We performed a Fourier analysis on the recorded sound signals produced by the water droplets. This analysis revealed a clear peak at 8000 Hz, with both the unfiltered and filtered sound. This is however lower than the 15000 Hz as described in the paper.

Velocity of the drop at different heights

We measured the velocity of falling water droplets at different heights. We did this experiment at different heights, because the droplets will have a different velocity at which they hit the surface of the water. As described in the Theory, there is a range of velocities where the droplet hitting the surface does make a sound. 

We found that when the droplet has a speed below 1.50m/s it will not make a sound when hitting the water surface. If the speed of the drop is above 2.20m/s the velocity is too high and the drop will not make a sound.