VIBRATION

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VIBRATION

• Sound and Noise

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Musical Sounds
Musical sounds provide relaxation and pleasure.
These are regular patterns. Sounds that can be
resaved on to recordings.
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Noise
Loud irregular patterns are called NOISE.
Prolonged periods of loud noise (irregular
patterns of sound) can cause temporary or
permanent loss of hearing.
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Sound Travels Through

• Gases (air)
• Liquids (sound travels 4 times faster through
  liquid than it does through air)
• Solids (sound travels the fastest in solids
  because
• the molecules are packed tightly together)

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Outer Space
Sound cannot travel through outer space because
there are no air molecules to carry the sound
waves.
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How We Use Sound
Instruments
Speech
Bells
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Vibration
Sounds from doors closing, ball bats hitting the
ball, dogs barking and musical instruments are
made when matter vibrates, or moves quickly back
and forth.
Vibrations can be made from Blowing
Stroking Plucking
Striking
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Pitch
Pitch is the highness and lowness of sound. When
you blow air into the (large) tuba, the air
vibrates slowly. The sound waves have long
wavelengths, and the sound has a low pitch. When
you blow air into the (small) piccolo, the air
vibrates quickly (fast). The sound waves have
short wavelengths, and the sound has a high pitch.
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SOUND WAVES
Experiments

• Make a big bang by bursting an air-filled paper
  bag. The air trapped inside the bag will send a
  powerful sound wave through the air that reaches
  our ears.
• Set up a row of dominoes by spacing them fairly
  close. Knock the first one over and watch how
  the wave travels.
• Sprinkle a few grains of uncooked rice on a paper
  and lay that paper over a radio and watch the
  rice jump as you turn up the sound.
• Place a ruler on the edge of a table and bend the
  ruler. Watch the ruler vibrate. Try changing
  the length that is over the edge. The shorter
  the length, the quicker the vibrations, the
  higher the sound. The number of sound waves a
  second is called the frequency of waves.

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Feeling Sound

• When something is making a steady sound then it
  must be vibrating to push the air back and forth.
• Place your hand
• On a purring cat
• On a ringing telephone
• On a radio or speaker that is playing loud music
• On your throat and count to ten

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ASSESSMENT

1. You hear sound through your________________.
2. Sound is made when matter ____________.
3. Objects that vibrate slowly have a pitch that is
   ____.
4. Objects that vibrate fast have a pitch that is
   _____.
5. Sound moves the fastest through ______________.
6. Sound moves the slowest through _____________.
7. Sound travels through all forms of _____________.
8. Sound travels louder through _______ than air.