Sound Waves

• Sound:

  • sound waves are produced by vibrating sources
  • a medium is required to transmit sound waves. (this means that if there are no molecules, then sound can't travel through it)
• Sound Waves - Longitudinal Waves:

  • sound waves are longitudinal waves.
  • longitudinal waves are where the particles of the medium vibrate back and forth in the same direction as the wave's movement.
  • longitudinal waves have alternative regions of compressions and rarefactions.
  • compression: region of higher density, place where the molecules are bunched together.
  • rarefaction: region of lower density, where the molecules are spread out.
  • When a sound wave propagates through air:
  • compression indicates areas of high air pressure.
  • rarefaction indicates areas of low air pressure.
• Transmission of Sound Waves:

  • sound travels at different speeds in different mediums:
  • sound travels fastest in solids
  • this is because particles are more tightly packed (high density), allowing sound vibrations to be transmitted quickly from one to another.
• Properties of Sound:

  • changes in amplitude and frequency affect the loudness & pitch of sound waves.
  • as frequency increases, pitch increases.
  • sounds with a high pitch have a high frequency (short wavelength)
  • sounds with a low pitch have a low frequency (long wavelength)
  • the amplitude of a sound wave is related to its volume (loudness)
  • sounds with a large amplitude have a high volume
  • sounds with a small amplitude have a low volume
• Behaviours of Sound Waves:

  • sound waves reflect off of hard surfaces
  • the reflection of a sound wave is called an echo