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Homemade Kazoo

Students create their own homemade kazoos to illustrate that sound vibrations can be seen, heard, felt, and amplified.

When you hum into the kazoo, vibrations from your vocal cords travel through the tube, vibrating the air molecules. The waxed-paper membrane that on the other end of the tube creates additional vibration, amplifying the sound.

The sound you make with your voice has a main pitch. But the distinctive sound of your voice is a result of harmonics, quieter vibrations at higher pitches. The harmonics are also amplified by the kazoo but not all of them are amplified by the same amount. That's why the kazoo makes your humming sound so weird.

When the kazoo's air hole is open, air can travel freely, and the kazoo sounds louder than when your finger covers the hole.

A typical kazoo given out at children's parties is a tapered plastic tube with a cap on it. The vibrating waxed paper or plastic is located in the cap. Simply blowing into the kazoo will not cause the wax paper to vibrate – it needs sound waves in order to vibrate.

Objectives

  • Describe the properties of sound.
    Describe what pitch is and how it varies.

Materials

  • a paper towel or toilet paper roll tube
    a square of waxed paper (approx. 7.5 cm by 7.5cm, or 3 inches by 3 inches)
    an elastic band
    a pair scissors or pen
    markers or paint or stickers
    a typical kazoo (optional)

Key Questions

  • What happens when you hum into the tube? Why does your voice sound different? Why does the loudness of your voice change?

What To Do

  1. Cut out a square of waxed paper that is 7.5 cm by 7.5cm (or have these already prepared).
  2. Tightly wrap the waxed paper over one end of the cardboard tube and secure it with an elastic band. Be careful not to apply too much pressure to the cardboard, it may cave in or bend. 
  3. Poke an air hole into the cardboard tube with scissors or a pen, right below the wax paper. Trim the waxed paper if necessary so it doesn’t cover the hole.
  4. Put the open end of the kazoo to your mouth and hum a tune.
  5. Feel the other end of the kazoo with your hand while you are humming.
  6. Decorate your kazoo with markers, paint, or stickers.

Extensions

  • Experiment with covering the hole with your finger, adding more holes in the tube oradjusting the amount of air you blow into it. How does it affect the sound? Why is wax paper needed? Could you use paper or plastic wrap instead?

Other Resources

Science World Resources | Full Unit | Sound