Sound Waves

1
Sound Waves

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

Click here for demo of mechanical properties.
http//www.ccohs.ca/images/noise1.gif
2
Speed of Sound

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

http//www.angelfire.com/scifi/dschlott/sSpeed.gi
f
3
Speed of Sound

• The speed of sound increases when the temperature
  is warmer.
• This is a direct relationship.

4
Speed of Sound

• Vin air 331 0.6(TC)
• Units are in m/s

5
Speed of Sound

• Example How fast does a sound wave move when air
  temperature is 10 C?
• V 331 0.6 (10)
• V 331 6
• V 337 m/s

6
Speed of Sound

• Sonic Boom Object is traveling faster than the
  speed of sound.
• MACH scale

http//community.webshots.com/photo/29220851/2922
4250NbiEGaCAdC
7
Click here for a Sonic Boom video
http//www.grc.nasa.gov/WWW/K-12/airplane/Images/
mach.gif
8
Sound Waves and Hearing

• Outer Ear visible part of ear, ear canal and
  eardrum. (Pg. 361)
• Energy from sound waves make the eardrum vibrate.

9
Sound Waves and Hearing

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

10
Sound Waves and Hearing

• Inner Ear The cochlea sends impulses to the
  brain.

11
Sound Waves and Hearing

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

https//secure.dca.net/nohr/Nohrcontactimages/Hai
r-cellbk.jpg
12
http//www.sickkids.ca/auditorysciencelab/images/
ohc_mild_sml.jpg
13
Intensity

• How much energy a sound wave carries over time.
• Determines how far it can travel.

http//www.safetyline.wa.gov.au/institute/level2/
course18/lecture54/images/noise11b.gif
14
Loudness

• The human perception of intensity.
• Measured in decibels (dB)

15
http//www.ednasia.com/cmsimages/issue0410cs5.gif

http//www.hearinginseattle.com/images/decibelbar
s1.jpg