1. The Nature of Sound and its Applications

2. Sound is produced by vibrations Sound is a compression(longitudinal) wave

3. Sound compresses particles together, then expands them causing compressions and rarefactions….like a speaker pushing and pulling particles together and apart

4. Sound requires a medium (solid, liquid, gas) in order to be heard The speed of sound depends on the medium and temperature Sound travels faster through solids, then liquids, slower in gases

5. Speed of Sound in Different media at 20 C Medium Speed (m/s) Air343 Helium1,005 Water1,482 Salt Water1,522 Wood-oak3,850 Glass4,540 Steel5,200

6. Pitch : how low or high you perceive a sound to be Frequency = number of waves per unit of time Pitch = Frequency Unit for Frequency = Hertz

7. Tuning Forks

8. High Frequency = High Pitch Low Frequency = Low Pitch Amplitude ( height of wave) = LOUDNESS Unit for loudness = Decibel (dB)

9. Infrasonic = lower than 20 Hz Ultrasonic = higher than 20,000 Hz Some common Decibel levels SounddB Level Whisper 20 Normal conversation 60 Chain Saw 100 Threshold of pain 120 Jet engine 140 Rocket engine 200

10. Reflection of Sound Waves = Echo Sound can travel around corners or through barriers = Diffraction Diffraction Tube Demo

11. Technological Applications Echolocation: the process of using reflected sound waves to find objects

12. Sonar is a type of echolocation as seen with the submarine. Sonogram is an example of ultrasonography.

13. Sonic Boom We hear a sonic boom when the sound waves reach our ears. Sonic boom is a form of constructive interference.

14. Interference of sound Waves Constructive Interference: Compressions of waves overlap, the sound will be louder Destructive Interference : Compressions overlap with rarefactions causing the amplitude to decrease (softer sound)

15. Resonance occurs when an object is vibrating at or near the frequency of a second object. Wine glass breaking when a lady sings Tacoma Bridge (utube video) Musical Instruments (drum-metal ring and tuning fork demo)