Chapter 13 Sound

  • Vibrating objects produce sound.
  • In humans sound is produced by vibration of the vocal cords.
  • Sound cannot travel in vacuum.
  • Sound can travel through a solid, liquid or a gas medium as well.
  • The vibration of sound are senses by the eardrum.
  • Eardrum is a stretched membrane.
  • Eardrum send signals to brain. This process is known as hearing.
  • Frequency of oscillation may be defined as the number of oscillation or vibrations in one second.
  • Hertz (Hz) is the unit of frequency.
  • The unpleasant and unwanted sound is called as noise. It may lead to noise pollution.
  • Many health hazards are produced by noise pollution.
  • Loudness of sound is called as amplitude or we can say the displacement of vibrating object from its main position is called amplitude.
  • Eardrum is a stretched membrane which separates the middle ear from the outer ear which vibrated to produce sound.
  • Larynx is known as the voice box which produces sound.
  • Loudness is the characteristics of sound which depends upon the amplitude.
  • Oscillation is the complete to and fro motion of an object about at its mean position.
  • Pitch is known as the flatness or shrillness of a sound.
  • Time period may be defined as the time taken by vibrating objects to complete one oscillation.
  • Vibration is the to and fro movement of a body.
  • Windpipe connects the larynx to the lungs, it is tube like structure of respiratory tract.

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Exercise 1 ( Page No. : 171 )

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