Sounds are caused when an object vibrates, causing vibrations in the medium through which it travels (generally air), which in turn cause vibrations in the ear drum of a listener. Faster vibrations create higher pitched sounds than slower vibrations.
To learn about pitch, you can approach the question from the point of view of the vibrations, or from the perception of the sounds.
Here are some activities for getting to know the vibrations:
- Stretch a balloon tightly over a jar with no lid to create a drum. Put Rice Krispies (grains of rice will work, but the cereal is lighter) onto the balloon and tap it gently. You will see the cereal moving as the vibrations travel across the balloon. If you have a drum, put the cereal onto the membrane on the head of the drum and it’ll work even better.
- Stretch out a Slinky and wiggle one end to create vibration. See how the vibration travels along the Slinky.
- Check out non-Newtonian fluids and how the vibrations of sound make them move. Just mix cornstarch and water and set it on top of a speaker. Crank up the bass and the volume — or watch it on this video, if you think that would make you unpopular in your hallway.
Here are some activities to approach pitch from the point of view of perception:
- Read stories like The Three Bears and The Three Billy Goats Gruff. Use low voices for the Papa Bear and the Big Brother Goat, medium voices for the Mama Bear and Middle Brother, and high voices for the Baby Bear and the Littlest Goat. Ask students to join you. When you finish, point out that this is about pitch and teach the word.
- Stand in a circle. Say “oooo” while simultaneously raising your hands above your head and raise the pitch of the “oooo” sound. Bring your hands and your pitch back down. Using your hands and the pitch of your voice, go up and down part of the way, stopping at different points and having students follow you. Then give students turns to lead the group.
- Play “Hunt the Thimble.” Have one student, It, cover his or her eyes. Hide a thimble (or another small object) somewhere in the room. It looks for the thimble while the rest of the class makes lower sounds for “colder” and higher sounds for “warmer.” Students can make the sounds with a syllable like “ta” or with the words “hotter” and “colder.”
Online resources:
- Artsedge has a lesson on strings and pitch as well as lessons on other instrument families and pitch. Perfect Pitch introduces ideas about pitch and instrument families.
- NIH resource on pitch and loudness
- Virtual Piano with frequency animations — quite fun.
- An applet for exploring pitch and frequency. This is clear and informative if you can stand it.
