1. Key Idea #3: Sound is created when something vibrates.
Energy is the ability to do work or cause motion.
Matter is anything that has mass and takes up space.
Sound energy is a disturbance made by vibrating molecules of matter that travel through a medium in the form of a longitudinal wave.

2. When a disturbance in the air reaches your ears, you hear the sound.
Two things are needed to hear sounds:
vibrating matter
a medium for the sound to travel through

3. Sound waves are a vibration that spread away from a vibrating object.
When molecules in matter vibrate, they cause other molecules near them to vibrate and waves travel outward from the center of the vibration.

4. FYI:The ear has 3 main sections
outer ear
middle ear
inner ear

5. The outer ear (p. 62) acts like a funnel collecting sound waves.
contains the eardrum. The sound waves make your eardrum vibrate.

6. The middle ear (p. 62) is behind the eardrum.
contains the hammer, anvil, and stirrup.
The eardrum vibrates the hammer, which vibrates the anvil, which vibrates the stirrup.

7. The inner ear (p. 63)
contains the cochlea which is shaped like a small shell.
The cochlea contains tiny hair-like structures

9. The speed of sound depends on the medium it is traveling through.

10. In a gas:
the molecules are very far apart resulting in a slower transmission of sound waves than in a liquid or a solid.
Examples:
human and animal hearing above the Earth’s surface
sonic booms

11. In a liquid:
the molecules are closer together allowing the sound to travel faster and farther than in a gas.
Example:
Dolphin and whale sounds travel farther through water than through the air.

12. FYI: Whale songs can travel for hundreds of miles underwater.
You‘ll need special equipment to listen to them if you are more than 10 miles away.

13. In a solid: the molecules are tightly packed.
more molecules can bounce off each other which results in an even faster transmission of sound.

14. Examples Sound travels through windows, doors, and walls.
Animals living underground can hear sounds through the earth.
Sound travels through the strings of musical instruments.
melindaklewis.com, howtee.info

15. Speed of Sound Chart
In which substance does sound travel the slowest?

16. Speed of Sound Chart In which substance does sound travel the slowest?
Sound travels the slowest in gases/carbon dioxide.

17. Speed of Sound Chart
In which substance does sound travel the fastest?

18. Speed of Sound Chart In which substance does sound travel the fastest?
Sound travels the fastest in solids/steel.

19. Speed of Sound Chart
What is the purpose of this graph?

20. What is this man doing and why?
soulcandyman.blogspot.com

21. What is this man doing and why?
The man is listening for a train.
He will hear the approaching train through the tracks before he will hear it through the air because sound travels faster through a solid than through a gas.
soulcandyman.blogspot.com

22. The “Old West”
People in the “Old West” put their ears to the ground to listen for hoof beats of buffalo or horses.
Why did they do this?

23. Sound can’t travel through a vacuum because there are no molecules in a vacuum to vibrate.
Sound can’t travel through outer space because the few molecules in outer space are too spread out.

24. Why does the speed of sound travel faster in warmer temperatures than cooler temperatures?
The speed of sound travels faster in warmer temperatures because the molecules are moving faster than the molecules in cooler temperatures.

25. Since sound is transferred by the collisions of molecules
the warmer, quicker moving molecules transfer the sound energy faster.
cooler, slower moving molecules result in a slower transmission of sound.

26. If you hit a tuning fork a sound is produced.
Question:
What causes the sound?

27. If you hit a tuning fork a sound is produced.
Question:
What causes the sound?
Answer:
Vibrations in the tuning fork cause the sound.

28. FYI: Review The pitch of a sound is directly related to the frequency of the sound wave.
Higher frequency sound waves create sounds with a higher pitch.
Lower frequency sound waves create sounds with lower pitch.
Changing the frequency of a sound wave changes the pitch of the sound.
Low Medium High

29. Speed of Sound Chart What is the purpose of this graph?
The purpose of this graph is to show how the speed of sound travels in different types of matter.

30. Doppler Effect (see fig 12 p. 50)
As a sound source moves toward the listener, the waves reach the listener with a higher frequency resulting in a higher pitched sound.
The pitch appears to increase because of the Doppler effect.
sciencerangers.com

32. The Doppler Effect

33. FYI: Sonic Booms (see fig 13 on p. 51)
learn.uci.edu

34. Music vs. Noise
Music is a set of tones that have a clear pitch and is pleasing to the ear.
Noise occurs when a sound wave has no smooth, regular pattern. It consists of a mixture of different vibrations. The wave is all mixed up.
Sound wave from a tuning fork has a smooth, regular pattern.
Sound wave from a hammer has an irregular, “spiky” pattern.