Talking Cups – SICK Science

How can cups talk? With a toothpick, some string, and some good vibrations!

From the soulful crooning of an R&B singer to the deep roar of thunder, sounds are created by vibrations. So, if you’re looking to make a cup speak, you have to find a way to make it vibrate. Combining the plastic cups with a toothpick and a length of string is the first step… but how do we make it talk?

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Experiment Materials

  • 16 oz plastic cup
  • Sharpened pencil
  • 12-18" String
  • Toothpick
  • Water
  • Paper towels

Experiment Videos

Experiment

1

Take a 16 oz plastic cup and poke a hole in the bottom with a sharpened pencil, just large enough for the string to fit through.

2

Thread a piece of string (12-18″ long) through the hole in the plastic cup.

3

Take the end of the string that is through the inside of the cup and tie it to a toothpick. Make sure that the toothpick is tied securely.

4

Pull the end of the string that is sticking out from the bottom of the cup until the toothpick catches on the cup. Give the string a couple of short but firm tugs to make sure everything is secure.

5

Now it’s time for this cup to talk! Fold a paper towel into quarters and use water to wet the towel. Pinch the string with the wet towel and slide the towel down the length of the string.

How Does It Work

Sound is created and transmitted through the air by vibrations. As your fingers slide across the string, they create small vibrations. When you add the wet paper towel, the string gets stickier and causes the “stick and slide” effect as you run your fingers down the string.  The “sticking and sliding” increases the strings vibrations.  The sound created by the vibrations is then amplified by the cup, creating the strange speaking sound.

Take It Further

Did you know that cups can alter their voices? Try making alterations to your apparatus to bring out different voices. Try:

  • Using yarn instead of string
  • Using a larger or smaller cup
  • Using longer or shorter lengths of string

What do your changes do to the cup’s voice?