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Sound is a wave

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Sound is a wave S8P4 a: Identify the characteristics of electromagnetic and mechanical waves. S8P4 d: Describe how the behavior of waves is affected by medium (such ... – PowerPoint PPT presentation

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Title: Sound is a wave


1
Sound is a wave
  • S8P4 a Identify the characteristics of
    electromagnetic and mechanical waves.
  • S8P4 d Describe how the behavior of waves is
    affected by medium (such as air, water, solids)

2
Vocabulary
  • Sound
  • Vibration
  • Vacuum
  • Echolocation
  • Sonar

3
Sound is a type of mechanical wave
  • Sound is a wave that is produced by a vibrating
    object and travels through matter
  • A vibration is a rapid, back-and-forth motion
  • The medium vibrates back-and-forth in the same
    direction as the disturbance, so sound waves are
    longitudinal waves.

4
Sound in our body
  • Sound-making instrument in your body is the vocal
    cords
  • Vocal cords relax when you breathe
  • They draw close together when you are about to
    speak so they can vibrate

5
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6
How sound waves are detected
  • Ear collects sound waves
  • Outer Earcollects the sound waves, reflects to
    the ear canal, hits the eardrum at the end of the
    ear canal and causes it to vibrate
  • Middle Earvibrations travel through three bones
    (hammer, anvil, and stirrup) to the inner ear
  • Inner EarCochlea, which contains tiny hairs that
    bend due to the vibrations, triggers cells to
    send electrical signals to your brain. Only when
    your brain receives and processes these signals
    do you actually hear a sound.

7
Animation of ear
  • file///D/Animation20List.html

8
  • Drum
  • Skin vibrates pushing particles in the air so
    they become compressed and moving out
  • When the drum pushes the opposite direction, the
    particles do not compress
  • longitudinal wave

9
Vacuum
  • A vacuum is empty space,
  • has no (or very few) particles
  • Robert Boyle proved that
  • sound does not travel
  • through a vacuum
  • Bell inside a sealed jar and
  • pumped all the air out, as
  • he pumped the air out, the
  • sound got quieter until it finally
  • quit

10
Important Info on Sound
  • Is a mechanical wave
  • Only moves through a medium made of matter
  • Cannot travel through a vacuumtherefore, it
    cannot move through space!

11
The speed of sound
  • Sound travels slower than light
  • Two factors that affect the speed
  • Material of medium
  • Temperature
  • Materials
  • Sound travels faster through liquids than gases,
    because of the amount of particles
  • Sound can travel through elastic solids very
    rapidly (steel)

12
The speed of sound
  • Temperature
  • Sound travels faster at higher temperatures than
    at lower temperatures
  • In hotter temperature the particles move faster
    making it easier to transfer sound waves
  • Sound waves will travel slower when someone yells
    in a snow storm than when someone talks softly on
    a hot summer day

13
Sound has many uses
  • S8P4 e Relate the properties of sound to
    everyday experiences.

14
Ultrasound Waves
  • Humans and Animals use ultrasound waves to detect
    objects
  • Bats use the echoes to find food
  • People use it to detect objects underwater and/or
    to produce images of the inside of the body
  • Sound waves are used for much more than just
    communication!!

15
Echolocation
  • Echolocation is the sending out of ultrasound
    waves and interpreting the returning sound echoes
  • Animals use echolocation to find food
  • Bats
  • Dolphins
  • Toothed Whales
  • Porpoises

16
Bats use sound to locate objects.
17
Sonar
  • People use the principle of echolocation to
    locate objects underwater which uses the echoes
    to produce an image on a screen
  • A sonar is an instruments that uses echolocation
    to locate objects (sonar stands for sound
    navigation and ranging)
  • Used to locate enemies (submarines)
  • Find lost ships
  • Find schools of fish
  • Map the sea floor

18
Medical Uses
  • Can be used at high intensities because it cannot
    be heard by humans, therefore will not damage our
    hearing
  • Used to
  • Break up kidney stones
  • Clean medical equipment
  • Examine internal organs like the heart, pancreas,
    bladder, ovaries, and brain
  • Examine blood flow

19
Medical Uses
  • Most common is the check on the health of a fetus
    during pregnancy
  • Helps determine gender of the baby
  • How many fetus there are
  • If there are any medical, or genetic, issues
  • The reflected ultrasound waves are used to create
    a picture called a sonogram

20
Ultrasound pictures Sonograms
21
Sound waves produce music
  • Music is sound with clear pitches or rhythms
  • Noise is random sound and has no intended pattern
  • All of the pitches, together with the resonance
    of the instrument, produce its characteristic
    sound

22
Musical Instruments
  • There are three main types of instruments
  • Stringed
  • Wind
  • Percussion
  • Will discuss these later!!

23
Sound can be recorded or reproduced
  • Back in the daythere was no way to record or
    reproduce our voices.
  • In the late 1800s, two inventions changed the
    world
  • 1876-the telephone was invented
  • 1877-phonograph was invented which was a sound
    recording machine

24
The telephone
  • Made long-distance communication possible
  • Telephones do two things
  • Translate the sound into a signal
  • Reproduce the sound that arrives as a signal

25
How the phone works
26
Recorded sound
  • This is a way to preserve sound because sound do
    not stick around, it is in real-time only
  • A recorder has a needle that takes the vibrations
    and cuts into a piece of foil. The grooves
    contain the information needed to reproduce the
    sound.
  • To play back, another needle is used to track
    along the foil
  • Now recorders change the sound waves into
    electrical signals as magnetic information
    instead of making holes
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