1. By: Cammie Goodman

2. When you hear a person talking, a dog barking, or a police siren, you hear sound. Most sounds are very loud. Others are soft. Sound sounds are high, like a whistle. Others are low, like a rumble of thunder.

3. Vibrations Make Sound
Remember that energy is the ability to make something move, happen, or change.
Sound is the energy that you can hear.
Sound is made by something vibrating.
When something vibrates, it moves back and forth very fast

4. Think about what happens when someone plucks a guitar string.
The string vibrates. Each time the string moves, it bumps against air that is nearby.
The string makes the air vibrate, too. The air bumps against more air, and so on.
The energy of the vibrations move through the air in waves.
Click Here for sound energy

5. The waves are like ripples in a pond when you toss a pebble into it
The waves are like ripples in a pond when you toss a pebble into it. Sound Wave Ripple Effect Animation
Sound waves travel from the guitar in all directions.
When the sound waves reach your ears, the air in your ear vibrates.
The air makes your eardrums inside your ears vibrate too.
Signals travel to your brain, and you hear the sound of the guitar.

7. Sounds Move through Matter
Sound can travel through materials, not through empty space. If you could clap your hands in outer space, it would not make a sound. Sound moves through solids, liquids and gases. It moves fastest through solid materials. It moves more slowly through liquids. It moves slowest through gases, such as air.

8. Did you know. Sounds can be so loud or strong that is shatters glass
 Did you know? Sounds can be so loud or strong that is shatters glass. This is because the glass absorbs the sound energy.

9. One property of sound is pitch.
Pitch is the highness or lowness of a sound.
If an object vibrates more slowly, it makes a sound with a lower pitch.
For examples, a small bell vibrates quickly, it has a high pitch.
A huge bell vibrates slowly. It has a low pitch.

11. An object that vibrates quickly makes sound waves that are close together.
Sound waves that are close together make a sound with a high pitch.
An object that vibrates more slowly makes sound waves that are farther apart.
Sound waves that are far apart make a sound with a low pitch.

12. You can change a sound’s pitch by changing how fast an object vibrates.
If you tighten a guitar string, it vibrates faster.
When the string vibrates faster, it makes a sound with a higher pitch.
If you loosen the guitar string, it vibrates more slowly. That makes a sound with a lower pitch.
Sound Waves

13. You can also change a sounds pitch by changing how long or thick the vibrating object is.
A short violin string has a higher pitch than a long violin string.
A thin string has a higher pitch than a long violin string.
In a flute or tuba, air vibrating in a tube makes sounds. Shorter tubes make sounds with a higher
Changing Sound - Click Here

15. Volume Another property of sound is volume.
Volume is the loudness or softness of a sound.
If you ring a small bell hard, it makes a loud sound. The sound has a high volume.
If you ring the bell gently, it makes a soft sound. The sound has a low volume. But no matter how hard you ring the bell, its pitch does not change. The bell still makes the same high sound. Only the volume of the sound changes.

17. When you ring a bell hard, you put a lot energy into moving it.
That energy changes into sound energy.
The bell makes sound waves that have a lot of energy and a loud volume.
When you ring the bell gently, the sound waves have less energy and a softer volume
Interactive Quiz

18. Click here for more animated sound videos

19. Discussion Question: What happens to the pitch and the volume of sounds when you turn up the volume on a music player?