1. EQ – How is life affected by energy? (Sound)
S8CS2 (Habits of Mind) & S8CS8 (Nature of Science
S8P4. Students will explore the wave nature of sound
a. Identify the characteristics of mechanical waves.
d. Describe how the behavior of waves is affected by medium (such as air, water, solids).
e. Relate the properties of sound to everyday experiences.
f. Diagram the parts of the wave and explain how the parts are affected by changes in
amplitude and pitch
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2. Originate from vibrating objects.
Sound Waves
Originate from vibrating objects.
The vibrating objects transfer this sound energy by direct contact with other matter (usually air).
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3. Sound Waves
Sound waves are classified as mechanical waves and they require a medium to transfer the energy.
The energy disturbance travels in concentric waves, spreading out from the source like ripples that spread out when a pebble is dropped in a puddle.
Sound waves are compression or longitudinal waves.
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4. Physical Characteristics of a Compression or Longitudinal Wave
Since sound is a longitudinal wave, it has the same characteristics previously studied: Wavelength = rarefaction to rarefaction or compression to compression;

5. Sound Waves Frequency (Pitch) – relates to
speed (v = λ x f); number of vibrations per second
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6. Sound Waves Amplitude - amount of energy
determines the loudness; NOT RELATED TO FREQUENCY OR WAVELENTH
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7. Speed of Sound The speed of sound depends on type of medium:
Liquids and solids transmit sound waves better than gases
The particles are closer together in liquids and solids making the transmission of energy easier
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8. Speed of Sound AND, the temperature of medium:
Higher temperature -- faster speed
Sound will travel slower in cold air on a winter’s day than it will travel in the warm air of a summer’s day
Why do you think this is?
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9. Sound travels slower than light:
Sound travels at 344 m/s through air at 20 C
Light travels at 300,000,000 m/s
Can you explain why the flash of a firework is seen before the sound of the firecracker explosion?
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10. Sound Wave Interaction
Interference is ability of two more waves to combine and form a new wave.
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11. Sound Wave Interaction
Constructive interference occurs when the compressions of two or more waves arrive at the same place at the same time. When this occurs, the compressions overlap and form a greater compression. As a result the sound will be louder.
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12. Sound Wave Interaction
Destructive interference occurs when the compressions of one wave overlaps the rarefactions of another
Wave thus decreasing the amplitude.
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13. Sound Wave Interactions

14. Blowing into the instrument causes the reed to vibrate.
Resonance (short & sweet)
Resonance is the transfer of energy from one system to another; or in other words resonance occurs when one vibrating body causes another body to vibrate at its natural frequency.
note: many musical instruments, especially stringed instruments, need something to increase the loudness of the sound i.e. guitar has a resonance chamber
Ocean Sounds?
Background noises cause the air inside the shell to vibrate and creates the sound of the ocean.
Blowing into the instrument causes the reed to vibrate.
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15. Doppler Effect
For sound waves, the Doppler effect is the apparent change in the frequency of a sound caused by the motion of either the listener or the source of the sound.
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16. THE END A special thanks to Pam McCann,
Diane Goldsberry, and Linda Trawick
for sharing their information and
ideas!
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