1. Table of Contents The Nature of Sound Properties of Sound Music
How You Hear Sound
Using Sound

2. Sound Waves - The Nature of Sound
Sound is a disturbance that travels through a medium as a longitudinal wave. As a gong vibrates, it creates sound waves that travel through the air.

3. Interactions of Sound Waves
- The Nature of Sound
Interactions of Sound Waves
Sound waves reflect off objects, diffract through narrow openings and around barriers, and interfere with each other.

4. The Speed of Sound - The Nature of Sound
The speed of sound depends on the elasticity, density, and temperature of the medium the sound travels trough.

5. Temperature and the Speed of Sound
- The Nature of Sound
Temperature and the Speed of Sound
The speed of sound in dry air changes as the temperature changes. The graph shows data for the speed of sound in air at temperatures from –10ºC to 20ºC.

6. Temperature and the Speed of Sound
- The Nature of Sound
Temperature and the Speed of Sound
Reading Graphs:
What is the speed of sound in air at –10ºC?
The speed at –10ºC is 325 m/s.

7. Temperature and the Speed of Sound
- The Nature of Sound
Temperature and the Speed of Sound
Interpreting Data:
Does the speed of sound increase or decrease as temperature increases?
The speed of sound increases as air temperature increases.

8. Temperature and the Speed of Sound
- The Nature of Sound
Temperature and the Speed of Sound
Predicting:
What might be the speed of sound at 30ºC?
At 30ºC, the speed of sound might be 349 m/s.

9. Elasticity - The Nature of Sound
Elasticity is the ability of a material to bounce back after being disturbed. You can model elasticity by representing the particles in a medium as being held together by springs.

10. Density - The Nature of Sound
Density is how much mass there is in a give volume. The volumes of the cubes are the same, but the brass has more mass.

11. Identifying Main Ideas
- The Nature of Sound
Identifying Main Ideas
As you read the section “Interactions of Sound Waves,” write the main idea–the biggest or most important idea–in a graphic organizer like the one below. Then write three supporting details that further explain the main idea.
Main Idea
Sound waves interact with objects and with other sound waves.
Detail
Detail
Detail
Reflection occurs when sound waves strike a surface.
Sound waves can diffract around corners and through openings.
The interference of sound waves can be constructive or destructive.

12. Click the SciLinks button for links on sound.
- The Nature of Sound
Links on Sound
Click the SciLinks button for links on sound.

13. End of Section: The Nature of Sound

14. Loudness - Properties of Sound
The loudness of different sounds is compared using a unit called the decibel (dB).

15. Pitch - Properties of Sound
The pitch of a sound that you hear depends on the frequency of the sound wave.

16. Changing Pitch - Properties of Sound
When you sing, you change pitch using your vocal cords. Your vocal cords are located in your voice box, or larynx.

17. The Doppler Effect - Properties of Sound
The change in frequency of a wave as its source moves in relation to an observer is called the Doppler effect. When a sound source moves, the frequency of the waves changes because the motion of the source adds to the motion of the waves.

18. The Doppler Effect - Properties of Sound
When the plane travels almost as fast as the speed of sound, the sound waves pile up in front of the plane. This pile up is the “sound barrier.”

19. Outlining - Properties of Sound
An outline shows the relationship between main ideas and supporting ideas. As you read, make an outline about the properties of sound. Use the red headings for the main ideas and the blue headings for the supporting ideas.
Loudness
Energy of a Sound Source
Distance From a Sound Source
Measuring Loudness
Pitch
Pitch and Frequency
Changing Pitch
Doppler Effect
What Causes the Doppler Effect?
What Causes Shock Waves?

20. More on the Properties of Sound
Click the PHSchool.com button for an activity about the properties of sound.

21. End of Section: Properties of Sound

22. - Music
Sound Quality
The sound quality of musical instruments results from blending a fundamental tone with its overtones. Resonance also plays a role in sound quality.

23. Groups of Musical Instruments
There are three basic groups of musical instruments: stringed instruments, wind instruments, and percussion instruments.

24. Previewing Visuals - Music
When you preview, you look ahead at the material to be read. Preview Figure 15. Then write two questions that you have about the diagram in a graphic organizer like the one below. As you read, answer your questions.
Musical Instruments
Q. How is pitch changed in each type of instrument?
A. By changing the frequency of the vibrations
Q. How is the loudness changed in each type of instrument?
A. By changing the energy of the vibrations

25. End of Section: Music

26. The Human Ear - How You Hear Sound
The outer ear funnels sound waves, the middle ear transmits the waves inward, and the inner ear transforms sound waves into a form that travels to your brain.

27. Sequencing - How You Hear Sound
Sequence is the order in which the steps in a process occur. As you read, make a flowchart that shows how you hear sound. Put the steps of the process in separate boxes in the order in which they occur.
How You Hear Sound
The outer ear funnels sound waves into the ear canal.
Sound waves make the eardrum vibrate.
Tiny bones in the middle ear transmit vibrations to the inner ear.
Vibrations in the cochlea of the inner ear send messages to the brain.

28. End of Section: How You Hear Sound

29. Echolocation - Using Sound
Some animals, including bats and dolphins, use echolocation to navigate and to find food.

30. - Using Sound
Sonar
A sonar device sends out ultrasound waves and then detects the reflected waves.

31. Comparing and Contrasting
- Using Sound
Comparing and Contrasting
As you read, compare and contrast echolocation and sonar by completing a table like the one below.
Using Sound
Feature
Echolocation
Sonar
Type of wave
Ultrasound
Ultrasound
Medium(s)
Air, water
Water
Find water depth, sunken objects,
schools of fish
Purposes
Navigate, find food

32. Click the PHSchool.com button for an activity about sonar.
- Using Sound
More on Sonar
Click the PHSchool.com button for an activity about sonar.

33. End of Section: Using Sound

34. Graphic Organizer Sound Longitudinal waves Intensity Frequency
travels as
has properties
Longitudinal waves
Intensity
Frequency
speed depends on
is heard as
is heard as
Elasticity
Density
Temperature
Loudness
Pitch

35. End of Section: Graphic Organizer