1. The Nature of Sound Physical Science Ms. Pollock 2009 - 2010

2. Sound  http://www.privateline.com/TelephoneHistor y/speech.jpg  All sounds produced by an object that vibrates Vocal cords loudspeakers

3. Sound Waves  Vibration causes air molecules to collide, transferring energy.  Collisions continue, transferring energy – sound wave  Compressional waves CompressionsCompressions rarefactionsrarefactions

4. Sound Waves  http://media-2.web.britannica.com/eb- media/20/4320-004-CFE3C8FE.gif

5. The Speed of Sound  Sound capable of traveling through all types of matter  Cannot travel through empty space  Faster through liquids and solids due to close particle spacing 347 m/s through air347 m/s through air 1498 m/s through water1498 m/s through water 4877 m/s through aluminum4877 m/s through aluminum

6. The Speed of Sound  Speed not dependent on loudness  Closer particles = faster transfer of energy  Speed dependent on temperature of medium Higher temperature = greater speedHigher temperature = greater speed Particles colliding faster and more oftenParticles colliding faster and more often

7. Human Hearing  Despite variations in sound, human ear capable of translating  Ears and brain working together to make sense of speech Ear gathers compressional wavesEar gathers compressional waves Ear amplifies compressional wavesEar amplifies compressional waves Amplified waves travel down nerve impulses to brainAmplified waves travel down nerve impulses to brain Brain decodes and interprets nerve impulsesBrain decodes and interprets nerve impulses

8. Human Hearing  http://www.hearingcare.com.au/hc/i mages/ear_diagram.jpg

9. Gathering Sound Waves – The Outer Ear  Visible part of ear, ear canal, eardrum  Visible captures waves and directs  Ear canal passageway to eardrum  Eardrum tough membrane that vibrates  http://www.sinuscarec enter.com/aao/images /39359796.jpg

10. Amplifying Sound Waves – The Middle Ear  http://www.worsle yschool.net/science /files/ear/ear2.gif  Hammer, anvil, stirrup  Multiply force and pressure produced by sound wave

11. Converting Sound Waves – The Inner Ear  http://www.hearin gcarecenter.com/i mages/ear.gif  Cochlea and tiny hair cells  Nerve impulses converted by cochlea sent through auditory nerve to brain  Usually location of damage when hearing loss is involved