Sound WavesSound Waves

• CompressionCompressional Waveal Wave

• Mechanical Mechanical Wave (must Wave (must have a have a medium)medium)

[http://www.ccohs.ca/images/noise1.gif]

Click here for demo of mechanical properties.

Speed of SoundSpeed of Sound

• Speed of sound is constant Speed of sound is constant in a given medium (chart in a given medium (chart pg. 359)pg. 359)

[http://www.angelfire.com/scifi/dschlott/sSpeed.gif]

Speed of SoundSpeed of Sound

•The speed of sound The speed of sound increases when the increases when the temperature is warmer.temperature is warmer.

•This is a This is a direct relationship.direct relationship.

Speed of SoundSpeed of Sound

•VVin airin air = 331 + 0.6(T = 331 + 0.6(TCC))

•Units are in m/sUnits are in m/s

Speed of SoundSpeed of Sound

•Example: How fast does a Example: How fast does a sound wave move when air sound wave move when air temperature is 10 temperature is 10 °C°C??

•V = 331 + 0.6 (10)V = 331 + 0.6 (10)•V = 331 + 6V = 331 + 6•V = 337 m/sV = 337 m/s

Speed of SoundSpeed of Sound

• Sonic BoomSonic Boom – – Object is Object is traveling faster traveling faster than the speed than the speed of sound.of sound.

• MACH scaleMACH scale

[http://community.webshots.com/photo/29220851/29224250NbiEGaCAdC#]

[http://www.grc.nasa.gov/WWW/K-12/airplane/Images/mach.gif]

Click here for a Sonic Boom video

Sound Waves and Sound Waves and HearingHearing

• Outer EarOuter Ear – – visible part of visible part of ear, ear canal ear, ear canal and eardrum. and eardrum. (Pg. 361)(Pg. 361)

• Energy from Energy from sound waves sound waves make the make the eardrum vibrate.eardrum vibrate.

Sound Waves and Sound Waves and HearingHearing

•Middle EarMiddle Ear – – Bones called Bones called the hammer, the hammer, anvil, and anvil, and stirrup stirrup amplify the amplify the sound.sound.

Sound Waves and Sound Waves and HearingHearing

• Inner EarInner Ear – – The cochlea The cochlea sends sends impulses to impulses to the brain.the brain.

Sound Waves and Sound Waves and HearingHearing

•Hearing loss Hearing loss is usually is usually caused by caused by damage to damage to the hair cells the hair cells in the in the cochlea.cochlea.

[https://secure.dca.net/nohr/Nohrcontactimages/Hair-cellbk.jpg]

[http://www.sickkids.ca/auditorysciencelab/images/ohc_mild_sml.jpg]

IntensityIntensity

• How much How much energy a energy a sound wave sound wave carries over carries over time.time.

• Determines Determines how far it how far it can travel.can travel.

[http://www.safetyline.wa.gov.au/institute/level2/course18/lecture54/images/noise11b.gif]

LoudnessLoudness

•The human The human perception perception of intensity.of intensity.

•Measured in Measured in decibelsdecibels (dB) (dB)

[http://www.ednasia.com/cmsimages/issue0410cs5.gif][http://www.hearinginseattle.com/images/decibelbars1.jpg]