what is sound ch 21.1 8th
DESCRIPTION
Information obtained from: Holt Science and Technology: Physical Science. New York: Henry Holt & Co, 2007. Print.TRANSCRIPT
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Chapter 21 Section 1
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Describe how vibrations cause sound
Explain how sound is transmitted through a medium
Explain how the human ear works, and identify its parts
Identify ways to protect your hearing
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Have you ever heard a sand dune sing??
http://www.pbs.org/wgbh/nova/sciencenow/3204/04-recipe.html
Some croak, squeak, whistle, or boom! Frequencies 500Hz - 2,500Hz
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Sound is created by vibrations
A vibration is a complete back-and-forth motion of an object
http://image.tutorvista.com/content/wave-motion-sound/longitudinal-waves-rarefaction.jpeg
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A longitudinal wave cause by compressions and vibrations traveling through a medium
Air particles vibrate back-and-forth along the path that the wave travels
Sound waves travel in all directions away from their source
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http://www.tpub.com/neets/book10/NTX1-14.GIF
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All sound waves require a medium
Sounds waves can travel through air, water, glass, and metal…
In a vacuum, there are no particles to vibrate (no sound)
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Your ears change sound waves into electrical signals
Outer ear: collects sound waves (funnels them in)
Middle ear: increases the size of the vibrations
Inner ear: organs change vibrations into electrical energy
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Outer ear: Pinna Ear canal
Middle ear: Ear drum Hammer, anvil, stirrup
Inner ear: Cochlea Hair cells, auditory nerve, brain
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http://www.uptodate.com/patients/content/images/PEDS/19566/Normal_ear_anatomy.jpg
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If a tree falls in the forest and no one is around to hear it fall, does the tree make a sound??
Making a sound vs. detecting a sound…
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Tinnitus – due to long term exposure to loud sounds Damage to hair cells or cochlea
(permanent) Ringing in the ears Can affect people of any age Can be prevented
http://www.druckkammerzentrum-traunstein.de/HBO_Dateien_Tinnitus/Tinnitus.jpg
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Block out loud sounds with ear plugs
Lower volume used on headphones
Move away from loud sounds
http://1.bp.blogspot.com/_tLoHEV37UR4/Rpe77Z_CdMI/AAAAAAAAAC0/y4sIc8UTxPk/s320/Tinnitus.jpg