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

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

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

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 331 m/s air 100˚ 343 m/s

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: 2,000 to 110,000 Hz humans: 20 to 20,000 Hz dogs: 67 to 45,000 Hz

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

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

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

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

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

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”

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

Bibliography Holt, Rinehart, Winston, North Carolina Holt Science & Technology, Holt, Rinehart, Winston, Orlando, 2005 Media College. COM, How sound waves work, http://www.mediacollege.com/audio/01/sound-waves.html, accessed 1/14/11 Google images, http://www.google.com/images, accessed 1/14/11