1. Tie a 50 cm length of string on each end of a wire coat hanger.
2. Wrap the other end of each thread around your forefingers.
3. Bend over so the coat hanger can swing freely and bump it against a wall or chair. What do you hear?
4. Try it again, but this time with your forefingers in your ears!
5. Try bumping it against different objects. Bend the coat hanger into various shapes. Does this make any difference to the sound you hear?
When you bump the coat hanger, it shakes or vibrates, making a noise. The noise is louder when your fingers are in your ears because the vibrations travel better through the tight string than through the air.