Make a Kazoo

Introduction

Do you remember your last parade, party, or fair? You might have been surrounded by sounds of all kinds: fireworks, music, and, maybe even the famous (or infamous) sound of kazoos. A kazoo is a very simple musical instrument, made up of a hollow pipe with a hole in it. They may be simple, but these little noisemakers are a great way to explore sound. In this activity you'll be investigating how kazoos work by building your own!

Materials

• Empty cardboard tube, such as an empty paper towel or toilet paper tube
• Plastic grocery bag. Alternatively, you can use parchment paper or wax paper.
• Aluminum foil (a square sheet, approximately four-by-four inches)
• Paper towel sheet (a square sheet, approximately four-by-four inches)
• Rubber band
• Sharpened pencil
• Scissors
• An adult to help
• Optional: Materials to decorate your kazoo (markers, wrapping paper, craft embellishments)
  
  
  

What Happened?

Each time you changed the structure of the tube, you probably noticed that the sound of your voice coming through the tube changed as well.

At first, when you spoke into the tube, you probably noticed that your voice sounded deeper or more resonant. This is because when you speak, sing, or hum into the tube, some of the sound bounces off the walls of the tube. You might also have felt the tube vibrate. Because of the sounds encounters with the tube, your voice sounds different when it travels through a tube. The change depends on the material of the tube.

After you covered the end of the tube, you most likely noticed that your voice sounded muffled. The covering created a barrier for the sound to pass through before reaching your ears, resulting in a much weaker sound. When you added the hole in the tube, it was probably again easier to hear the sound of your voice. The hole in the tube allowed some air (and sound) to escape and reach your ears without losing its strength.

Your voice might also have sounded amplified and more resonant when the end of the tube was covered. If so, the thin plastic at the end of the tube vibrated in response to your voice. The extra vibrations added to the existing ones, amplifying the sound. These vibrations might also have given the sound a different quality. Different coverings will vibrate differently, and thus, affect the sound in a different way.

Digging Deeper

A kazoo is a very simple musical instrument, made up of a hollow pipe with a hole in it. The end of the pipe is covered by a membrane that vibrates, resulting in a buzzing sound when people sing, speak, or hum into the pipe. People have been making and playing kazoos for years. The first kazoos were made from hollowed out bones, with spider egg sacs used for the vibrating membrane!

Although a kazoo looks and feels more like a flute or clarinet, it's actually most closely related to a drum. As the player sings, speaks, or hums into the open end, the vocal cords vibrate, creating sound waves that travel through the instrument. As they travel through the tube, some of the sound waves bounce off the walls of the instrument. This change in direction can add harmonics to the sound of the player's voice (depending on the material of the tube); however, most of the sound waves strike the membrane, causing it to vibrate. This vibration adds resonance or harmonics to the sound and creates the characteristic buzzing that we associate with the kazoo. Resonance is when additional sound waves are identical to the initial sound wave. They add to the initial sound and thus increase its volume. Harmonics also add to the initial sound but are not identical to it. They change the quality or timbre of the sound.

Thin plastic, aluminum foil, and paper towel are thin pliable materials that can vibrate in response to sound. You may have noticed that the aluminum foil and paper towel coverings did not create the same vibrating quality to your voice as the thin plastic covering did. Neither the aluminum foil nor the paper towel is quite as effective in amplifying sound. The aluminum foil is less flexible than the thin plastic, so it did not vibrate in the same way as the plastic did in response to your voice. As a result, sound may have bounced off the foil without amplifying it. When stretched taught, it is possible that the aluminum foil vibrated, adding a metallic quality to the sound. In contrast, the paper towel is too porous. Air—and thus sound waves—can pass directly through it without causing it to vibrate. Most likely, only the thin plastic membrane vibrated in a way that made your voice sounded amplified and vibrant.

For Further Exploration

• Compare different-size cardboard tubes or tubes of other materials. Does the sound of your voice change with different-size tubes or with a tube of an other material?
• Poke additional holes in the cardboard tube. Does this change the sound of your voice when you speak into the tube?

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