Hit that fork! What does it sound like?
What you need:
- Piece of string between 30-100cm
- Tie the fork to the centre of the piece of string.
- Take one of end the string and tie it loosely to your right
- Take the other end of the string and tie it loosely to your
left index finger.
- Put your fingers gently on your ears.
- Ask your volunteer to gently tap the fork with the spoon.
What can you hear? Try tying other metal objects to the string.
Do they sound different? Could you tie a few objects to the string
and make a tune?
When the volunteer hits the spoon, the spoon vibrates. These
vibrations travel up the string and into your ear. The vibrations
make your eardrums vibrate. Your eardrums send a message to your
brain and your brain translates the vibrations into sound.
Vibrations travel at different speeds through air and string.
This is why the sound of a spoon hitting a fork sounds different
with the string near your ears.
Different metal objects vibrate at different speeds. This makes
your eardrum vibrate at different speeds. Your brain translates
this into different sounds.