Turn it down!

Listen: Dolphins "scream" to each other over human-made noise pollution

Originally Published: 
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If you’re trying to talk to your friend at a loud concert, your first instinct might be to raise your voice.

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Dolphins do something similar: When swimming in loud environments, they whistle louder and more frequently to communicate with their peers, according to a new study.

However, there are times when it gets too loud for dolphins to hear each other.

Human activities like drilling and shipping can cause a significant amount of noise pollution in wild dolphin habitats.

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Writing this week in the journal Current Biology, researchers demonstrate that high volume can seriously hinder dolphins’ ability to work together.

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Dolphins are social creatures that hunt and swim in groups and use their calls to communicate.

Even in captivity, whistling across the water can help them carry out cooperative tasks.

For the study, researchers trained two captive dolphins, Delta and Reese, to press buttons on opposite sides of a lagoon at the same time.

Sorensen et. al, Current Biology

Here’s the pair successfully completing the task.

Sorensen et. al, Current Biology

Equipped with recording devices, Delta and Reese chattered to each other as they completed the task over increasingly louder background noise — for a total of 200 attempts.

Sorensen et. al, Current Biology

At the highest levels of noise, failures like this one became more common.

Sorensen et. al, Current Biology

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During trials with no added background noise, Delta and Reese were able to complete the task 85 percent of the time.

But at the loudest level of sound, they were only 62.5 percent successful.

As the human-made sounds got louder, the dolphins raised their voices, and their whistles became longer.

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The dolphins also turned toward each other as they approached each button, likely to increase the chance that they could hear the others’ call.

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But loud levels of noise still proved hard to cut through, demonstrating that disruptive, human-made sounds could have a detrimental effect on animal communication and cooperation.

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