Many species of whales and dolphins are known to have supersensitive hearing because they use sound to navigate through echolocation. The clicks they produce as part of this process bounce off objects as small as a ping pong ball 20 meters away. This sensitive hearing ability makes these mammals particularly susceptible to loud sounds in the ocean.

In 2008, researchers at the University of Hawaii, Honolulu (USA) began to suspect that some marine mammals could protect their hearing naturally. They found that a captive false killer whale, a species of large dolphin, could adjust hearing sensitivity when trained to know that an impending sound would be loud.

“That’s similar to a human putting in foam earplugs,” team leader Paul Nachtigall, a marine biologist and director emeritus of the Marine Mammal Research Program at the Hawaii Institute of Marine Biology in Kailua, told Science magazine. “It’s really fascinating to be able to have that switch inside of your head.”

Techniques have been suggested using this knowledge to help reduce the impact of ocean noise on sea animals. “Any efforts to come up with ways to mitigate impacts of human-caused noise [are] both needed and welcomed,” says Robin Baird, a biologist at the Cascadia Research Collective in Olympia (Washington State, USA), who was not involved with the work. However, whether these techniques will work in the real ocean environment remains an open question.

Source: Science magazine