Transcript primary_underwater_sound_pp

Underwater
Sound
“A learned society advancing marine
science through research,
communication and education”
Life Around the Turbines resources are free and can be downloaded from www.mba.ac.uk/education
The Marine Environment
o The marine environment is full of
noise.
o Some of the noise is natural.
o Some of the noise is man made.
o Can you think of any noises you
might hear?
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Sound and Water
o Sound can travel 5 times faster in water
than air.
o Sound can travel great distances
underwater.
o A whale’s song can travel up to 3,000 km.
o Sound can be bounced off objects
underwater (an echo).
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Marine Mammals have developed
their hearing for many reasons
o Hunting
o Navigation
o Communication
…they depend on sound to sense the ocean
around them, find food and travel.
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Dolphins and Echolocation
o Some animals use echolocation to determine the
distance from objects including food and
predators.
o Dolphins use sonar clicks.
o Clicks bounce back when they contact an object
(echo).
o If the object is close the sound returns fast.
o If the object is far away it will take longer to
return.
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o A dolphin can detect a golf ball sized
object which is placed over a
football field away.
o A dolphin’s sense of hearing is much
more developed than it’s sense of
sight.
o Why do you think that is?
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Communication
o Marine animals use sound
to communicate.
o As sound travels well in
water, some animals can
communicate over great
distances.
- Blue whales can hear each
other up to 1,000 miles
apart.
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Where do sounds come from?
Man made examples:
o
o
o
o
Wind farms
Ships
Drilling
Sonar
Image: Ashley Dace
Natural examples:
o
o
o
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Waves and rocks
Wind
Marine mammals
Birds
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Noises from Wind Farms
o Construction:
 Hydraulic hammers
 Offshore pilling
o Operation
 Ships that service the
wind farms.
Image: Thom Gordon
Image: Gary Faux
Image:
Gary
Faux
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Impacts of noise on marine
mammals
o Unnatural background noise can
interfere with the sense of hearing
of marine mammals.
o This can make it harder for them to
hunt, navigate and communicate.
o This is called masking.
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o Different frequencies have different
effects…
o Noise trauma - damages hearing and long
exposure can cause permanent loss of
hearing.
o Mammals may avoid noisy areas. This
can be a problem if these are important
feeding or breeding grounds.
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Reducing Damage
o The offshore wind industry can try to
reduce the damage caused by noise
pollution in the sea:
• Drilling monopiles instead of
hammering them
• Slow start pile driving
• Using floating turbines or other
alternatives to monopiles
• Using sound barriers such as air
bubbles and foam wrapping
• Using pingers to scare off mammals.
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What have we learned?
o Sound travels very well in water.
o Marine mammals have an excellent
sense of hearing and use sounds for
many things.
o Background noise and noise pollution
affect the hearing of marine mammals.
o A lot of this noise can come from human
activities including wind farms.
o It is possible to reduce human noise
pollution in the sea.
www.mba.ac.uk/education
www.mba.ac.uk/education