This experiment demonstrates the effect of vibrations on pitch tone. The science is used in the making of woodwind instruments. Try this easy experiment at home and make your own orchestra (we can't promise it will sound like classical music though!)
What you will need
- 1 balloon - that's all!
How to do it
- Inflate the balloon but don’t tie it off.
- Hold both sides of the neck of the balloon with your finger and thumb.
- Pull the neck apart and listen to the sound it makes.
- Try to adjust the sound by increasing and reducing the distance that you stretch the neck.
- See how else you can adjust the sound by experimenting.
What is happening?
As you stretch the neck of the balloon you reduce the space for the air to flow out of the balloon. The air flow causes the neck to vibrate and it is this vibration that makes the squeaky noise. When you don’t pull very hard, the vibrations are small so the sound is a higher pitch. But if the neck is stretched further the vibration waves are deeper and the sound is a lower pitch. This science is the basis of woodwind instruments played in a band or orchestra…although hopefully sounding a bit better than a squeaky balloon!
Share your experiment...
All experiments must be conducted in the safest possible way. An adult must be present wherever it states one is required. Never do anything dangerous with chemicals or fire for your sake and those around you.