Introduction: Water Sound Experiment

About two months ago, Our team (Koray Budwiloitz, Léon Verhoef and myself) started a first year course at the Technical University Delft in the Technical Physics department named DEF (Design Engineering for Physicians). In this course we were instructed to design and build a (demonstration) practicum to display a physical phenomenon. We searched the internet for ideas and saw this video on youtube come by and decided to remake this experiment. The change we wanted to make compared to the youtube video, was the addition of a pump to reuse the water.


  • 1 drip tray/ big bucket
  • 1 bilge pump
  • 1 speaker (if it is a separate speaker, use a standard)
  • 1 rubber water hose
  • 1 function generator
  • 1 connecting piece between the speaker and function generator
  • 1 (telephone) camera with 24 fps
  • 1 (telephone) camera standard
  • water
  • duck tape

Step 1: Setup

Follow the next instruction:

  1. place the bilge pump inside the bucket
  2. connect the rubber hose to the bilge pump
  3. fill the bucket with water
  4. test the water speed to see if the bucket is large enough
    • the water speed should be the same as a standard home water tap
    • the water should not squirt out (hard jet), but neither should it be a very soft jet (preferably use a middle hard jet)
  5. place the speaker (with a standard) above the bucket
  6. attach the hose on top of the expandable area of the speaker (with duck tape). when attaching note the following:
    • the hose should not touch the stationary part of the speaker. When this happens, place a small wooden block or cork between the hose and the speaker
    • the end of the hose should flatten slightly horizontally
    • the hose should move as freely as possible, so that is has a large deflection
    • the water should be redirected into the bucket
  7. connect the function generator to the speaker (with the connecting piece)
  8. finally, place the standard of the (telephone) camera so the camera faves the end of the hose

Step 2: Demonstration

Follow the next instruction:

  1. set the function generator to (approx.) 24Hz and use the maximum voltage the speaker can handle
  2. turn the bilge pump and athe speaker/function generator ON (a diverging beam is now visible)
  3. set the (telephone) camera to 24 fps (the diverging beam should now be standing still in zigzag line on the screen)
  4. change the frequency a bit to see the beam move up, down and stand still

The effect can be optimised by:

  • using a bigger speaker with a bigger amplitude
  • using the accurate hose diameter for the speaker (the bigger the speaker, the bigger the diameter of the hose can be)
  • changing the pressure on the hose so the water speed is not too fast, but neither too slow
  • using a (telephone) camera with a better resolution