1. How Do Sound Waves Travel?
Chapter 12 Lesson 3
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2. How Do We Hear Sounds?
When the vibrations travel through air and reach your ears, they make your eardrum vibrate.
Those vibrations travel through bones and tissues until they reach your inner ear.
Special cells in your inner ear change the vibrations into electrical signals.
The electrical signals travel along a nerve to your brain and it recognizes the signals and you hear the noise!

3. Your Ear How Hearing Works
Outer Ear- catches sound waves and funnels them inward to your eardrum.
Eardrum- the sound waves make your eardrum vibrate. Vibrations from the eardrum travel along three tiny bones, called the hammer, anvil, and stirrup.
Cochlea- Bones pass vibrations to a snail-shaped organ called the cochlea. Hairlike cells inside change vibrations into nerve signals.
Nerve signals from the cochlea travel along this nerve to your brain. 1 3 2
How Hearing Works

4. Reflection
Light waves and Sound waves are behave in a similar way when they come in contact with surfaces.
When sound waves hit a flat, smooth surface, they are reflected back in the same pattern. This is what causes an echo.
When sound waves hit a rough surface, they are scattered all over.
The sound waves are bouncing off the surface, a process called reflection.

5. A flat, smooth surface preserves the pattern of the sound waves.
A rough, uneven surface destroys the pattern of the sound waves.

6. Absorption
Some materials stop the sound waves from reflecting or traveling any farther. This process is called absorption.
Walls, curtains, carpet, etc. “absorb” the vibrations and thus cause there to be no more sound.

7. Transmission
You can hear sounds when waves keep vibrating through some kinds of material.
They travel through air or other matter, all the way to your inner ear.
The sound waves keep moving through the material to produce sound– a process called transmission.
When we hear someone in another room, the sound waves are being transmitted through the air in that room, through the wall, through the air in your room, and then into your ear.
Materials that can vibrate are materials that can transmit sound.
How do sound waves travel through different materials?

8. Quietly take out your remote

9. ______ means that sound waves keep moving through materials to produce sound.
Reflection
Absorption
Transmission

10. A wave’s bouncing off a surface is called ___________.
Reflection
Absorption
Transmission

11. __________ stops sound waves from traveling any farther.
Reflection
Absorption
Transmission

12. An echo Silence A jumble of sounds
Suzy yells her friend’s name very loudly. What might she hear when the sound waves bounce off the smooth surface of a cliff?
An echo
Silence
A jumble of sounds

13. Which part of the ear acts as a funnel for sound waves?
Cochlea
Eardrum
Hammer, anvil, and stirrup
Outer ear

14. Sound waves cause which part of the ear to vibrate first?
Cochlea
Eardrum
Hammer, anvil, and stirrup
Outer ear

15. In which part of the ear are vibrations changed to nerve signals?
Cochlea
Eardrum
Hammer, anvil, and stirrup
Outer ear

16. Carpet absorbs sound waves.
True
False