sound waves

• • sound waves are longitudinal waves
  • they are caused by vibrations that pass through solid, liquid or gases
• • sound waves cannot travel in space because space is a vacuum
  • so, no particles are able to move
  • so, not able to carry vibrations to produce sound
• • sound waves travel faster in solids than in liquids
  • sound waves travel faster in liquids than in gases
• how do we hear sound?

  • sound waves enter ear canal and cause eardrum to vibrate
  • vibration pass along ossicles through canal to cochlea
  • cochlea turns vibrations into electrical signals
  • electric signals pass through auditory nerve to brain
• • high frequency sound waves are high pitched
  • low frequency sound waves are low pitched
• • high amplitude sound waves are loud
  • low amplitude sound waves are quiet
• • sound waves are reflected by hard and flat surfaces
  • echoes are reflected sound waves
• • sound waves refract as they enter different media
  • they speed up as they enter denser material
• • when waves travel into different medium, the wavelength changes but the frequency stays the same
  • so, the speed must change
• • the speed of sound in air is 330 m/s
• • the range of human hearing is 20Hz to 20,000Hz (20 kHz)