1. 11.1 Sound travel
How does sound travel?
Sound is made by vibrations.
It is heard by your ears and brain.
How does it get from a vibrating object to your ears?

2. 11.1 Sound travel
How does sound travel?
The vibrations from an object set the particles in the air around it vibrating.
The vibrations move from particle to particle and the sound moves through the air.
Eventually it hits your ear.

3. 11.1 Sound travel
How does sound travel?
Sound moves through air particles in a very regular pattern of vibration.
It moves as a wave.

4. 11.1 Sound travel
Sound waves
A good model of how sound waves travel is a Slinky.
The video file shows the energy from a vibration moving as a wave through a Slinky.

5. The picture shows one wave following another through a Slinky:
11.1 Sound travel
Sound waves
As the energy passes through the Slinky, it pushes (or compresses) the coils together. This is called compression.
The picture shows one wave following another through a Slinky:
compression

6. 11.1 Sound travel Sound waves
As the energy is transferred forward to the next coils, those are pushed together and the ones behind spread out (rarefaction).
compression
rarefaction

7. 11.1 Sound travel
Sound waves
Watch the video again carefully to see what happens to the springs as the wave passes through.

8. 11.1 Sound travel
Sound waves
When the wave has passed through the Slinky, all the springs are in the same place as they were before.
A wave like this travels through a material like air, water or metal but the material itself stays where it is.

9. 11.1 Sound travel
Sound waves
This model in the animation shows how the vibrations from a tuning fork form waves through the air.

10. 11.1 Sound travel
Sound waves
Why doesn’t sound travel through a vacuum?
Why does sound travel faster in liquids and solids than it does in air?