Sound Vibrations: Rubber Band Music

Sound is a form of energy that travels in waves. Sound is produced by the vibration of matter. A stringed instrument such as a guitar or violin produces sound when the strings vibrate. The pitch of the sound varies from high to low, depending on how fast the string vibrates. Pitch is dependent on factors such as the diameter, tension, and length of the string. In this activity you will find out how the diameter of a string affects its pitch.

Materials

Very thick rubber band

Medium-thick rubber band

Thin rubber band

Activity

1. Put the thin rubber band over your five fingers and stretch your fingers so the rubber band is only lightly stretched.
2. Pluck the rubber band and listen for the pitch of the sound.
3. Stretch the rubber band farther by spreading your fingers. Repeat step 2.
4. Stretch the rubber band using both hands so it is very taut. Repeat step 2.
5. Repeat steps 1 through 4 with the medium-thick rubber band and then with the very thick rubber band.

Follow-Up Questions

1. When you increased the stretch of each rubber band by spreading your fingers, did the pitch of the sound increase or decrease?
2. Which of the three rubber bands had the highest pitch when it was held in its tautest position?

Answers

1. Increase.
2. The thinnest rubber band had the highest pitch.

Extension

Position a wooden ruler on a desk or table so the majority of it extends off the edge. Gently push down and let go of the free end of the ruler so it vibrates up and down. Shorten the length of the ruler extended over the desk's edge and repeat this process. How is the loudness of sound affected by the length of the ruler?