KEY CONCEPT
Sound is a wave.
BEFORE, you learned
NOW, you will learn
• Waves transfer energy
• Waves have wavelength,
amplitude, and frequency
• How sound waves are
produced and detected
• How sound waves transfer
energy
• What affects the speed of
sound waves
STANDARDS
8–6.3 Summarize
factors that influence
the basic properties of
waves (including
frequency, amplitude,
wavelength, and
speed).
8–6.5 Explain hearing
in terms of the relationship between sound
waves and the ear.
EXPLORE Sound
What is sound?
PROCEDURE
1
Tie the middle of the string to the
spoon handle.
MATERIALS
• piece of string
• large metal
spoon
2 Wrap the string ends around your left and
VOCABULARY
sound p. 469
vibration p. 469
vacuum p. 473
right index fingers. Put the tips of these
fingers gently in your ears and hold them there.
3 Stand over your desk so that the spoon dangles
without touching your body or the desk.
Then move a little to make the spoon tap
the desk lightly. Listen to the sound.
WHAT DO YOU THINK?
• What did you hear when the spoon tapped the desk?
• How did sound travel from the spoon to your ears?
Sound is a type of mechanical wave.
OUTLINE
Start an outline for this
heading. Remember to
leave room for details.
I. Main idea
A. Supporting idea
1. Detail
2. Detail
B. Supporting idea
In the last chapter, you read that a mechanical wave travels through a
material medium. Such mediums include air, water, and solid materials.
Sound is an example of a mechanical wave. Sound is a wave that is
produced by a vibrating object and travels through matter.
The disturbances that travel in a sound wave are vibrations. A
vibration is a rapid, back-and-forth motion. Because the medium
vibrates back and forth in the same direction as the wave travels,
sound is a longitudinal wave. Like all mechanical waves, sound waves
transfer energy through a medium.
What do sound waves have in common with other mechanical
waves? Your answer should include the word energy.
Chapter 14: Sound 469