Dolphins 'shout' at each other over increasing levels of underwater noise pollution.
Dolphins have to 'shout' at each other due to increased noise pollution
Experts suggest that sounds made by humans force the animals to make louder and less effective whistles and there are fears about the impact noise has on marine life.
Dolphins use echolocation to hunt and reproduce and human activities such as drilling and shipping could have an impact on wild dolphin populations.
Pernille Sorensen, a graduate student at the University of Bristol and first author of the research, said: "In a very noisy pub we find ourselves increasing the volume of our voice. Dolphins respond in a similar way - they're trying to compensate but there are some miscommunications."
She added: "Within the last couple of decades, we've seen a dramatic increase in human-made noise, and noise pollution in the oceans is no exception.
"Those same reasons that make sound so advantageous for animals to use also make them susceptible to disturbance from noise in the environment."