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Sound Waves. Sound Waves. mechanical, longitudinal waves require a medium may pass through solids, liquids, or gases medium particles move parallel to the motion of the wave has compressions and rarefactions. Speed of Sound. about 342 m/s in air changes with temperature
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Sound Waves • mechanical, longitudinal waves • require a medium • may pass through solids, liquids, or gases • medium particles move parallel to the motion of the wave • has compressions and rarefactions
Speed of Sound • about 342 m/s in air • changes with temperature • much slower than light • speed of light = 300,000,000 m/s
Loudness or Intensity • Sound Simulator • amplitude (energy) of a wave • describes how loud or soft a sound is • measured in decibels
Loudness or Intensity • Soft • Low energy • Loud • High energy
Pitch • Sound Simulator • frequency of a wave • measured in Hertz • how high or low a sound is
Pitch • Low f, low pitch • Large wavelength • High f, high pitch • Small wavelength
Pitch & Human Hearing • Humans hear between 20-20,000 Hz • Ultrasound – too high f for humans to hear • Infrasound – too low f for humans to hear
Doppler Effect • as a sound producing object approaches a receiver (listener) the sound’s pitch increases (high f) • the waves appear to sound higher
Doppler Effect • as the object moves away, the pitch drops (low f) • the sounds appears to sound lower
Doppler Effect • occurs for other types of waves as well, but is easiest to relate to sound waves
Doppler Effect • Used to: • Predict weather • Tell instant speed of moving objects • Track galaxies
1999 Oklahoma City F 5 Tornado St. Nazianz storm May 12, 2000. Caused some schools to be extended.
Acoustics • How sound interacts with surroundings
Refraction Reflection • Why does sound travel a long distance over water? • Sound waves bounce off the flat surface of a lake • Sound waves refract off of warm air over a lake Warm Air Cool Air
Room and Building Acoustics • Sound behavior in a room depends on many factors: • Volume • Shape of room • Echo patterns
Room and Building Acoustics • Construction Material • Energy absorbing: foam, wood, carpet • Energy reflecting: metal, concrete
Room and Building Acoustics • Audience layout • Furnishing • Source of Sound