Noise pollution

• Civil noise - aircraft design and location

  • location away from major populations
  • land use restrictions near airports
  • taxi areas away from residential areas
• Civil noise - aircraft engine design

  • high bypass ratio engines ( smooths flow of exhaust air)
  • chevron nozzles ( high bypass engines even quieter
  • engine acoustic liners ( to absorb noise)
• Civil noise - aircraft body design

  • Blended wing aircraft( engines on top of aircraft, body acts as barrier reducing noise towards ground)
  • Lighter aircraft ( carbon fibre, less thrust needed)
• Civil noise - control of noisier aircraft

  • restricted flight times ( night flights banned near urban areas)
  • Quota Count System ( Aircraft types given points based on noise levels, allocated certain no. of points) Used at Heathrow
• Railway noise

  Sources and control:

  • WHEEL VIBRATION - track polishing
  • ENGINE NOISE - sound absorbing suspension
  • BREAKING SQUEAL - composite materials
• Road traffic noise

  Affects MORE people than other forms of noise.

  Source and control:

  • WHEEL NOISE - sound absorbing road materials, porous asphalt
  • ENGINE NOISE - engine acoustic insulation
  • ACOUSTIC BARRIERS - fences, embankments, dense trees
  • Doubled glazed buildings
• Industrial noise

  Source and control:

  • COMPRESSORS/ PUMPS - silencers reduce explosive expansion of air
  • MINE BLASTING - regular timing, baffle mounds
  • Sound absorbing materials in equipment
  • Worker ear protection
  • Sound absorbing material around equipment
• Effects of noise

  OBJECTS:

  • acoustic fatigue - cracking and structural failure
  • vibration damage - affect buildings and underground pipes

  HUMANS:

  • hearing damage - exposure in job
  • Stress health problems - high blood pressure

  OTHER ORGANISMS:

  • livestock - sudden noise cause panic, could lead to injury
  • disturbance of breeding birds - sing for mates, scared birds leave their nests
  • reduced feeding success - animals that use sound to find food ( dolphins)