Please note: The effect cannot be seen with the naked eye, so anyone who wants to try it at home will have to first get their hands on a camera capable of shooting at exactly 24 frames per second.
Explanation: ‘When the frequency of the speaker is the same with the frequency of the video frames (frames/sec) the camera actually captures the same frame everytime and thus the same water shape. ‘You can see the change 1hz makes when filming (if filming is kept at the same rate 24fps) as this translates into a “forward movement”. ‘Imagine a clock with only a seconds indicator. If you would close your eyes and open them precisely once every 60 seconds you would think the indicator is not moving.’