Use a balloon to amplify sound!
Small sounds can be made to sound like a big noise if you use a good sound conductor. We can demonstrate this with a balloon, air and your own ears.
What you’ll need:
1. a balloon
1. Blow up the balloon.
2. Hold the balloon close to your ear while you tap the other side.
What’s really going on?
Even when you tap only lightly on the other side of the balloon, this noise seems quite loud to your ears. When you blew up the balloon, you forced the air molecules inside the balloon closer to each other. As the molecules are closer together, the sound waves travel more easily making the balloon a good conductor of sound. It is a better conductor of sound than the air around you as those air molecules are spaced further apart.