Step 1: Materials
Driver for the speaker (I had one laying around but you can build your own, use a guitar amp, etc)
Plastic lid that is about 4 inches – 6 inches in diameter with about a ½ inches lip to contain the fluid
Hot Glue Gun
Wire strippers, electrical tape, etc.
Clear Plastic wrap (this is optional but when using corn starch it can replace the lid and just cover the speaker for some cool results)
Frequency generator (A downloadable program called AudioTest was used for this project)
Step 2: Preparing the Speaker
Essentially this device is just a lid glued to a speaker. This will allow the vibrations from the speaker to be transferred directly into whatever fluid is in the lid allowing you to observe patterns. The other part of the setup is wiring the speaker to the driver. The author recommends the cutting wires long enough so that your speaker can sit on the table and be far enough to not splash any water on the sensitive electronics.
Step 3: Running the setup with water
To use this device simply pour water into the lid and play some sounds out of the speaker. If you play a slow sweeping wave you might be able to find out at which frequencies the fluid resonates as there will be a well defined pattern. The fun part of this is experimenting and changing up these frequencies to produce cool patterns in the water allowing you to visualize sound.
Step 4: Running the setup with corn starch
Running the setup with cornstarch is definitely more fun than watching the water. When mixing cornstarch with water, the author recommends a 2:1 cornstarch to water ratio. The important part is to make sure that the cornstarch resists sudden stirring motions. The author also states that the cornstarch mixture responds better at lower frequencies and higher amplitudes when compared to the water. It is also recommended to remove the lid and place plastic wrap over the speaker. Pouring cornstarch onto the plastic wrap, allows the cornstarch to bounce around. You can also add food color for added contrast and color.