Sound

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Sound
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Sound waves

• are caused by vibrating matter
• Longitudinal waves

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Sound

• Travels through solids ,liquids and gases

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Matter

• all matter is made up of molecules
• these vibrate

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Sounds as Longitudinal waves

• Compression's and rarefractions

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Factors affecting the speed of sound

• Type of matter
• Elasticity and density
• faster in dense elastic matter

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Temperature

• Temperature increases the speed of sound increases

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The Sound Barrier

• Occurs when you travel faster than the speed of
  sound

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Sound Barrier

• Chuck Yeager broke the sound barrier on October
  14 , 1947
• X-1 rocket plane

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Properties of Sound

• Intensity - loudness
• more energy
• Amplitude

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Decibels

• Loudness can be measured
• Decibel (dB)
• falling leaves 10 dB
• Jet engine 170 dB

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Intensity

• Sounds greater than 120 dB are considered to
  cause pain
• Constant exposure to high decibels can cause
  hearing loss

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Frequency and Pitch

• How high or low a sound is determines its pitch
• Changing your Pitch changes the frequency
• Measured in Hertz

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Doppler effect

• The change in pitch as the source moves or the
  observer moves

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Sound Quality

• timbre is the blending of different-frequency
  sound waves that produce sound quality
• Different instruments have different qualities

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Sound wave Interactions

• Reflection of sound - Sound is reflected and
  absorbed when it meets a barrier
• Echoes

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Refraction of sound

• You can hear better at night
• Sound travels faster in cooler temperatures
• The waves refract up -day
• The waves refract down - night

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Diffraction of sound

• Can you hear around corners - Yes
• Sound waves diffract
• Low frequencies diffract better

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Sound Interference

• Constructive and destructive interference occurs
  when sound waves from more than one source meet
• Example Rock Concert

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Resonance

• Objects vibrate at their natural frequencies this
  vibration is called resonance