Noise Pollution Flashcards by Study Sets

What is noise?

Sound which is unwanted

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How is sound produced?

Vibrations passing through air, liquid or solid But not a vacuum

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What is the effect of noise on objects?

If noise causes an object to vibrate at its natural resonate frequency this may result in stress cracks which is an indication of acoustic fatigue

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What sort of infrastructure can be structurally damaged by repetitive vibration?

Roads
Bridges
Buildings
Aircraft

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What are the physiological effects of noise on organisms?

Muscle constrictions
Increased heart rate and blood pressure
Constriction of blood vessels
Stress
Irritability
Head aches
Temporary or permanent damage to hearing

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What can be over stimulated or die from loud noises?

Microscopic hair cells which line the organ of corti in the cochlea of the inner ear when dead hearing loss is permanent

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What ways do animals use sound?

Navigation
Finding food
Attracting mates
Avoiding predators

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How does noise pollution affect animals?

Makes it difficult for them to survive by interfering with sound

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What marine organisms rely upon sound?

Whales
Dolphins

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What do whales and dolphins rely on sound for?

Echolocation to feed, communicate, navigate and find mates sound interferes with this

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What is an example of birds being affected by noise?

Bluebirds in noisy areas have fewer chicks

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How are cows affected by noise pollution?

Cows equipped with bells tend to decrease head movements to avoid generation of the sound thereby reducing the amount of pasture plants removed

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How can chronic noise stress affect male animals?

Male sex hormone and causes changes in reproductive organs and glands
Increased serum corticosteroids causing 80% decline in testosterone concentration

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What is chronic noise stress?

Prolonged above 100db

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What actions may be intensified by loud noises? (In animals)

Flight reactions- galloping, random movements, biting/ kicking

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What is frequency?

Number of waves per second

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What is the unit for frequency?

Hertz (hz)

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What is the hertz range for humans?

Can detect frequencies between 20 and 20,000 sensitive between 1000-4000

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What is the abbreviation for decibel?

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What sound does the decibel scale measure?

All sound types

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What is the decibel scale?

measure of the size of the fluctuations in the air pressure caused by sound waves

What doesn’t the decibel scale measure?

Sound volume

What type of scale is the decibel scale?

Logarithmic- 10db increase doubles intensity

Why is the decibel scale logarithmic?

Because of the wide range of human hearing response

What type of sound is the DBA scale used for?

Used for human hearing so only sound available to humans (20-20,000 hz)

What is the NNI scale?

Noise number index

What does the NNI measure?

Number of flights and the noise level of aircraft over 80db

How are the results from the NNI presented?

Range of 0-70 with aircraft noise being unreasonable in level of 50-60

How much of outside noise comes from transport?

66%

What is road vehicle noise a combination of?

Engine noise Exhaust noise vibration of the tyres on road surface

What is a baffle mound?

barriers made of earth, wood, metal or concrete or composites may reduce noise levels by 10-15dB

What is the problem with baffle mounds?

Houses above the height of the barrier wont be protected

What are some mechanisms to reduce traffic noise?

Traffic calming Engine enclosure Seal exhausts joints effectively Fans turned off when not needed Buffer zones or barriers Traffic flow management Build new roads below the level of the land surface Use porous asphalt for road surfaces Improve housing insulation

What is the principle with traffic calming?

Slows traffic reducing tyre noise

What is the principle with engine enclosure?

enclosure absorbs noise

What is the principle with seal exhausts joints effectively?

Reduce vibration

What is the principle with fans turned off when not needed?

Reducing number of of moving parts

What is the principle with buffer zones or barriers?

absorb noise

What is the principle with traffic flow management?

Ban lorries at times or places Control flow by sequencing traffic lights

What is the principle with building new roads below the level of the land surface?

Embankments absorb and reflect noise

What is the principle with using porous asphalt for road surfaces?

Texture helps absorb noise 20% of its volume is pore space thus water infiltration is rapid, reducing noisy spray

What is the principle with improving house insulation? (noise pollution)

Double/ triple glazing + composite wall material absorbs sound

What is railway noise a combination of?

Engine noise Vibration of wheels on track

How can railway noise be controlled?

Timing freight and passenger movement (ban between 12am-5am) Ballasts

Why are ballast used on railways?

Aggregates under and between the tracks absorb noise

What is domestic noise a combination of?

Appliances (TV, dishwasher) Garden equipment Music

How can you control domestic noise?

Insulation e.g. double insulation to absorb or reflect noise Considerate use

How can industrial noise be reduced?

Reduce weight and height of impacting masses Reduce speed of spinning parts Reducing pressure and flow velocities of circulation systems Enclosing in acoustic insulation Using dampening materials (viscous liquid to dissipate energy)

How can workers be protected from industrial noise?

Using ear protectors Limiting exposure to the noise

How can airport noise be reduced?

Lighter (reduce engine power) Aerodynamic shape Engine smaller but more efficient Better brakes Limit weight carried in plane Limit flight times Reduce air ports bear high density urban areas