Noise pollution Flashcards
Effects of noise pollution on living organisms
HUMANS
-headache
-burst eardrum
-permanent damage
-hearing loss
-increased stress levels
-heart problems (increased blood pressure)
-behavioural changes (easy anger)
-communication problems
Effects of noise pollution on living organisms
OTHER
-unable to call for young/hear young
-disturbance to livestock (panic, injury, failure to breed)
-disturbance of breeding birds
-sudden noises to leave nets/eggs
-reduce feeding success
-struggle to hear pray
-citations, whales and dolphins susceptible to sonar (military) linked to mass beaches
effects of noise pollution on non living organism
-vibrations
-shatter (glass)
-sonic boom (travelling faster than speed of sound)
-acoustic fatigue (stress cracks)
Measuring noise
The decibel scale
loudness of a sound
Measuring sound
The dB (A) scale
-decibel sound adjusted for human hearing
-o level is the lowest level we think humans can hear
Measuring sound
LA10
-measures noise levels at its worst
-nosiest (10%)
Measuring sound
LA90
(road traffic)
-measures the noise levels in the quietest end of the scale
Measuring sound
L1018h (traffic noise)
(road traffic)
same as LA10 but in an 18hr period
Measuring sound
Traffic noise index (TNI)
(road traffic)
-a full picture of what people are being subjected too
Measuring sound
effective perceived noise levels EPNL
(aircraft)
-estimate of noise during take off, flying and landing
-a relative scale (interested in whether if it’s noisier in comparison to noise levels)
Measuring sound
Noise and number index NNI
(aircraft)
-combines number of flights and noise levels of aircraft above 80 decibels
-below 80 doesn’t count as annoyance
Measuring sound
Leq 57dB
(aircraft)
-average sound level over a particular period.
-UK airports have an average of 57dB
-between 7am-11am is used
Sources of aircraft noise
-engine noise
-turbines
-landing, take off, breaking
-air moving over wings
-air being drawn into engine and expelled
-drag, friction (resistance)
Reduction of aircraft noise through Airpot design
-building airports always from domestic property’s
-have run way away from domestic properties
-taxing areas away from residential properties
-airplane test centres (safety checks/MOTs) away from domestic properties
-multiple landing runways (less reverse thrusting/quieter landing)
-upgrading windows (mitigating)
-surround airports with barriers to absorb noise (vegetation)
-restriction areas around airport, so not used for domestic props
Reduction of noise through engine/aircraft design
-chevron nossles encourage batter mixing of air decreasing noise levels
-improvement of aerodynamics reduction of drag and resistance
-covered fairings anything that protrudes and smoothing them to make them more aerodynamic
-blended wing aeroplanes only used for smaller military aircraft’s
-light weighting of aircraft use of aluminium or carbon fibre, for things that don’t require high strength
-high bypass ratio engine
has air moving around engine that mixes with air exiting the engine before released, so air release is moving at a similar speed to outmoded air creating less noise
-acoustic liners have material around the engine that absorb noise
-engine hush kits work like chevron nossles , work with high bypass ratio
reduction of noise by airport operation
-time restrictions on take off and landing
-restricting or banny of nosier aircraft’s
-regularly changing flight paths (incoming and outgoing) people less subjected too noise
-steep angle of ascent, taking off as steep as possible (noise however, much higher up in sky and quicker)
-shallow landing at a constant land of decent (when coming down not using engine a lot less nosier)
-quota count system- airports given total number of points, each aircraft have winter flights as don’t want to use up points. Can have many quiet planes or few noisy planes
-night time flight restrictions
Other noise sources
Railway sources and control/ reduction measure
1.wheel vibrations-polishing the track, use of gravel as sound absorbing ballast
2.engine noise-sound absorbing suspension
3.pantograph turbulence-aerodynamic faring
4.wheel squeal on corners- lubricator of wheels/track
5.barking squeal-use or composite material brakes
6.wheel noise-good carriage suspension
