Can Sound Travel Through Things?

Procedure

1. Start with a mini lesson about how sound travels. Here is some background information:

Imagine what happens when you drop a stone into a pool of water. Waves ripple out from the spot where the stone entered the water. The way waves move across the water is similar to how sound waves travel through the air.

When you speak or shout, your vocal chords vibrate . These vibrations travel in all directions through the air as waves. When the waves reach our ears, they make our eardrums vibrate too, so we can hear the words.

But to get to our ears, sound waves need to travel through the air, which vibrates. Air is made up of particles, that move to make the sound waves. The vibrating object, like your vocal chords, bump the air particles next to it. They then bump the particles next to them, and so on until the moving particles reach someone's eardrums.

Most of the sounds we hear travel through the air, but sound waves can also move through water, wood, and metal. You can test this out for yourself. Everything that you can see has particles that can vibrate. But if there's no particles, there's nothing to bump into, so sounds can't travel. For example, in outer space, there are no particles to bump into, so sounds can't travel. No particles means no vibrations, and no vibrations means no sound waves, which means no sounds.

In movies and on TV, you'll sometimes see and hear things exploding in outer space -- alien spacecraft and things like that. The explosions can make the story more exciting, but in real life, you wouldn't be able to hear an explosion in outer space.

Instructions for the Project:
2. Drop the spoon onto a table. Observe the sound it makes. Write up your observations in your journal.

3. Tie a piece of string to the middle of the spoon, allowing approximately 15 to 20 inches of string on either end.

4. Wrap the ends of the string around your index fingers, dangling the spoon in front of you. Make sure that both ends of the string are taut.

5. Place your index fingers in your ears.

6. Tap the spoon against the edge of the table. What sound does it make? Does it sound the same as when you dropped it on the table earlier? Write your observations down in your journal.

7. Tap the spoon against other things in the room, and observe the sounds you hear. What happens if you strike things gently, or with more force? Write your answer in your journal.

8. How do you think you can hear the sounds the spoon makes, even though your fingers are in your ears? Write about your observations.

Brought to you by Tom Snyder Productions