1. SOUND
SOUND
SOUND
Kim Lachler
Updated 2015
NCES: 6.P.1.3

2. Sound Is: Potential changing to Kinetic Mechanical Longitudinal
- moves
Mechanical
– needs a medium to travel
Longitudinal
- Particles vibrate back and forth to the energy

3. Speed of Sound Is affected by the type of medium
\\LEBUNVSMS01\VOL2\USERS\STAFF\KIMLACHLER\Desktop\Introduction_to_Sound_Waves.mov
Is affected by the type of medium
The closer the molecules are together the faster it can travel
Fastest – solid
Medium – liquid
Slowest - gas

4. Speed of Sound Is affected by temperature
Particles of a colder medium travel slower than a warmer medium.
This results in sound traveling faster in a medium that is warmer.
air 0˚ C m/s
air 100˚ m/s

5. Pitch and frequency
Pitch is how low or high a sound seems to be depending on the frequency. (It is NOT how loud it is)
* Frequency number of waves produced in a given amount of time
-The higher the frequency the higher the pitch
*Expressed in Hertz 1 Hz = 1 wave per second
bats: ,000 to 110,000 Hz
humans: to 20,000 Hz
dogs: to 45,000 Hz

6. Pitch and frequency The Doppler effect
An observed change in the frequency of a wave when the source or observer is moving.

7. Loudness and Amplitude
Energy_and_Sound__Loudness_and_Frequency.mov
Loudness is the extent to which a sound can be heard
Amplitude of a wave reflects the amount of energy in the wave
The more energy the larger the amplitude, the louder the sound
Sound is measured in decibel (db)
0 db softest sound you can hear
60 db normal conversation
120 db threshold of pain
200 db rocket engine 50 m away

8. Interactions of Sound Waves
Reflection – Echo
The bouncing back of a sound wave.
Sound waves reflect best on smooth, hard surfaces.

9. Interactions of Sound Waves
Reflection – Echo
Echolocation – process of using reflected sound waves to find objects.
Animals – bats and dolphins

10. Interactions of Sound Waves
Reflection – Echo
Echolocation Technology
Sonar (Sound Navigation and Ranging)
Submarines and fisherman
Ultrasound -Turns sound waves into pictures.
Development of the fetus and soft tissue organs

11. Interactions of Sound Waves
Interference
Sonic boom
When a jet reaches the speed of sound the waves in front cause constructive interference creating the sound barrier.
When the jet breaks through the sound waves spread out behind it in a cone.
When the sound reaches you (not when the jet goes through) you hear the “sonic boom”

12. Interactions of Sound Waves
Resonance
2 objects vibrate at the same natural frequency
Trumpet and guitar

13. Bibliography
Holt, Rinehart, Winston, North Carolina Holt Science & Technology, Holt, Rinehart, Winston, Orlando, 2005
Media College. COM, How sound waves work, accessed 1/14/11
Google images, accessed 1/14/11