Transcript Nature of Sound Waves

Sound Waves
• Compressional
Wave
• Mechanical
Wave (must
have a
medium)
Click here for demo
of mechanical
properties.
[http://www.ccohs.ca/images/noise1.gif]
Speed of Sound
• Speed of sound is constant in a
given medium (chart pg. 359)
[http://www.angelfire.com/scifi/dschlott/sSpeed.gif]
Speed of Sound
• The speed of sound increases
when the temperature is
warmer.
• This is a direct relationship.
Speed of Sound
• Vin air = 331 + 0.6(TC)
• Units are in m/s
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
Speed of Sound
• Sonic Boom –
Object is traveling
faster than the
speed of sound.
• MACH scale
[http://community.webshots.com/photo/29220851/29224250NbiEGaCAdC#]
Click here for a
Sonic Boom
video
[http://www.grc.nasa.gov/WWW/K-12/airplane/Images/mach.gif]
Sound Waves and Hearing
• Outer Ear –
visible part of
ear, ear canal
and eardrum.
(Pg. 361)
• Energy from
sound waves
make the
eardrum vibrate.
Sound Waves and Hearing
• Middle Ear –
Bones called
the hammer,
anvil, and
stirrup amplify
the sound.
Sound Waves and Hearing
• Inner Ear –
The cochlea
sends
impulses to
the brain.
Sound Waves and Hearing
• Hearing loss is
usually caused
by damage to
the hair cells
in the cochlea.
[https://secure.dca.net/nohr/Nohrcontactimages/Hair-cellbk.jpg]
[http://www.sickkids.ca/auditorysciencelab/images/ohc_mild_sml.jpg]
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]
Loudness
• The human
perception of
intensity.
• Measured in
decibels (dB)
[http://www.hearinginseattle.com/images/decibelbars1.jpg]
[http://www.ednasia.com/cmsimages/issue0410cs5.gif]