1. CHAPTER 14 SECTION 2

2. SOUND
–a wave of vibrations that spreads from
its source.
• Vibration is the back-and-forth motion of
an object.

3. Crest - areas where particles are very
close together
Frequency - The number of crests that
pass by a point each second
The greater the frequency is, the higher
the pitch of the sound

4. Why Are Some Sounds Louder
Than Others?
• The source of the louder sounds
is vibrating more.
• These sound waves have more
energy.
• A sound’s loudness can be
measured in units called
decibels.

5. YOUR VOICE
• Your vocal cords vibrate when you talk.
• The vibrations are caused by air rushing past
them.
• Your vocal cords make the particles in the air
around them vibrate.
• These vibrations travel outward through the
air as sound waves.

7. How Does Sound Behave?
• Sound can travel through solids,
liquids, and gases
• It cannot travel through a vacuum,
which is empty space that contains no
particles
• The speed at which sound waves
travel is different in different
materials.

8. Sound Transfers Energy
• For a sound to be heard, energy must first cause
an
object to vibrate.
• Vibrating objects give off energy in sound waves in
air.
• Some of the energy reaches your ear, and your
eardrum absorbs some of the energy.
• In this way, the energy
of the original material’s
vibrations passes to you.

10. SOUND
–a wave of vibrations that spreads from
its source.
• Vibration is the back-and-forth motion of
an object.

11. Crest - areas where particles are very
close together
Frequency - The number of crests that
pass by a point each second
The greater the frequency is, the higher
the pitch of the sound

12. Why Are Some Sounds Louder
Than Others?
• The source of the louder sounds
is vibrating more.
• These sound waves have more
energy.
• A sound’s loudness can be
measured in units called
decibels.

13. YOUR VOICE
• Your vocal cords vibrate when you talk.
• The vibrations are caused by air rushing past
them.
• Your vocal cords make the particles in the air
around them vibrate.
• These vibrations travel outward through the
air as sound waves.

14. How Does Sound Behave?
• Sound can travel through solids,
liquids, and gases
• It cannot travel through a vacuum,
which is empty space that contains no
particles
• The speed at which sound waves
travel is different in different
materials.

15. Sound Transfers Energy
• For a sound to be heard, energy must first cause
an
object to vibrate.
• Vibrating objects give off energy in sound waves in
air.
• Some of the energy reaches your ear, and your
eardrum absorbs some of the energy.
• In this way, the energy
of the original material’s
vibrations passes to you.