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Sound

Sound. How is sound formed? How does sound travel? Speed of Sound? Echo Sound Intensity, Frequency, and pitch The Doppler Effect. How is sound formed?. Sound - Form of energy that travels in waves and can be perceived by the ear Formed through vibrations

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Sound

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  1. Sound How is sound formed? How does sound travel? Speed of Sound? Echo Sound Intensity, Frequency, and pitch The Doppler Effect

  2. How is sound formed? • Sound - Form of energy that travels in waves and can be perceived by the ear • Formed through vibrations • back and forth movements of particles • All sounds formed by vibration • Ex. Guitar Strings plucked and vibrated • Vocal Cords vibrating and causing voice

  3. How does sound travel? • Sound travels in Longitudinal Waves or compression waves • Particles in air (or other mediums) vibrate (move back and forth) in the direction of wave motion • Sound does not travel in a vacuum • There are no particles in a vacuum • SOUND NEEDS A MEDIUM TO TRAVEL THROUGH

  4. Do you hear what I hear? • As sound vibrates particles through the air, the sound wave is sent from source of sound to your ear • Vibrations travel to ear drum causing it to vibrate • Vibrations in eardrum travel to middle ear where 3 bones (malleus, incus, and stapes) vibrate • Send vibrations to Cochlea in inner ear where nerves send messages to the brain to analyze sounds.

  5. Speed of Sound • Sound travels at 340 meters/second • Sound travels much slower than light • Sound: 340 meters/second • Or (.340 km/second) • Light: 299, 792, 458 meters/second • (or 300,000 km/second) • Lightning and thunder

  6. Sonic Boom (Breaking the Sound Barrier) • Supersonic speed • Faster than the speed of sound • Breaking the sound barrier • At supersonic speeds objects push back air particles ( in this case vibrating particles due to sound) • See some jets before you hear them • Break glass

  7. Echo • Echo – Sound reflected from a barrier • Sound reflection • Angles, non-porous walls, marble • Bounces back to source • Sound absorption • Sound does not echo • Carpet, cloth panels

  8. Echolocation and SONAR • Bats can determine location using high frequency sounds that bounce off objects • SONAR • Sound Navigation And Ranging • Used to find geography of ocean floor • Find schools of fish

  9. Sound Intensity • Intensity – the amount of energy a sound has • Large amplitude = Louder Sound • Sound intensity measured in Decibels (dB) • Break a glass with your voice alone

  10. Sound Frequency and Pitch • Pitch - How high or low a sound is • Related to frequency • High frequency sound = High pitch • Low Frequency sound = Low Pitch • Humans • 20 Hz and 20,000 Hz

  11. Ultrasonic Sound • Sound beyond our normal hearing range • Whales • Bats • Dogs

  12. The Doppler Effect • Doppler Effect – The apparent change in the frequency of waves • The frequency of sound seems to change when the source of sound moves toward or away from you

  13. http://www.google.com/url?sa=i&rct=j&q=doppler+effect+police+siren&source=images&cd=&cad=rja&docid=QxJ-R3W2VtIfMM&tbnid=WUQNWrIinMt79M:&ved=0CAQQjB0&url=http%3A%2F%2Fasset.emsofl.com%2FONLINE%2520CLASS%2FPhysLifeCD%2F_CDDAT%2FPhySci8%2Funit09%2Fphschool.com%2FSE_O_SC2_ACT.html&ei=C8U9Ud_JJ42xqwGX3YCYCQ&bvm=bv.43287494,d.aWM&psig=AFQjCNEADVNJYCTTTAaFgCtRo32uc8DDfw&ust=1363089032704957http://www.google.com/url?sa=i&rct=j&q=doppler+effect+police+siren&source=images&cd=&cad=rja&docid=QxJ-R3W2VtIfMM&tbnid=WUQNWrIinMt79M:&ved=0CAQQjB0&url=http%3A%2F%2Fasset.emsofl.com%2FONLINE%2520CLASS%2FPhysLifeCD%2F_CDDAT%2FPhySci8%2Funit09%2Fphschool.com%2FSE_O_SC2_ACT.html&ei=C8U9Ud_JJ42xqwGX3YCYCQ&bvm=bv.43287494,d.aWM&psig=AFQjCNEADVNJYCTTTAaFgCtRo32uc8DDfw&ust=1363089032704957

  14. The Doppler Effect • Occurs when there is motion between source of sound and observer • As sound approaches waves seem close together and have high frequency • As sound passes waves seem farther apart and have lower frequency

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