words per minute
6
AmanSSC
00:00
Speed
The sounds produced by large marine mammals are of a similar low frequency range to
much of the noise produced by humans. The noise produced by ships tends to be less
which overlaps with the vocal frequencies produced by many large mammals. For example,
Blue whales produce frequency vocalisations of less than 100 Hz, meaning their calls can be
lost in the background din. Shipping noise has led to marine mammals altering their
vocalisation patterns. This includes making calls longer and more repetitive or waiting until
noise levels drop before calling. Research has shown that shipping noise made within 1200
metres of humpback whales and has caused the whales to either reduce or stop their calling
the waters surrounding, the remote Islands in Japan. Despite these vocal adaptations noise
can negatively affect feeding behaviour of animals and increase physiological stress. Research
found that a reduction in shipping led to a six decibel drop in noise levels in the Atlantic
coast of Canada. This coincided with lower levels of physiological stress and detected in
North Atlantic. The right whales, when researchers measured stress, a substance produced
from floating whale waste material. Noisy oceans are having a profound negative impact on
marine life. Taking action to protect and restore natural soundscapes is a key priority for
conservation nowadays. The good news is that noise is removed from the environment as
soon as the sound source is switched off or turned down. Technological developments in ship
design such as reduced propellor cavitation the formation of air bubbles on the surface of a
propeller have already lowered the noise produced by ships. Small adjustments in
speed can also substantially lower engine and propeller noise. Research has found that a
large amount of reduction in the average speed of commercial ships can reduce underwater
noise pollution by more than fifty percent. But global awareness of the impact of noise on
ocean health needs improvement.