A beluga whale learned to talk like human just by listening to human conversations. Its ability to mimic human voice was so good that once a diver thought someone in the water was actually talking to him, says a new study.

According to the National Marine Mammal Foundation, the beluga whale called NOC could imitate human voice.

"The whale's vocalizations often sounded as if two people were conversing in the distance. These 'conversations' were heard several times before the whale was eventually identified as the source. In fact, we discovered it when a diver mistook the whale for a human voice giving him underwater directions," said Dr. Sam Ridgway, President of the National Marine Mammal Foundation.

Researchers at NMMF recorded the whale's voice both underwater and in air and studied the physiology behind the whale's ability to imitate human voice.

The study on the beluga whale, NOC, is published in the journal Current Biology.

Ridgway isn't the first person to discover a "talking whale". In the 1940s, scientists discovered that a group of beluga whales mimicked human voices and the sounds were almost like "children shouting in the distance", according to Nature.

The beluga whale stopped talking like a human around four year after its mimicking abilities were discovered. Researchers say that the loss of speech might be because the whale had matured.

"When NOC matured, we no longer heard speech-like sounds, but he did remain quite vocal. While it's been a number of years since we first encountered this spontaneous mimicry, it's our hope that publishing our observations now will lead to further discoveries about marine mammal learning and vocalization," Ridgway said in a statement.

According to Peter Tyack, a marine biologist from the University of St. Andrews in Scotland, the study on NOC is important because it shows that whales can produce "completely new sounds in its repertoire just by listening", according to National Geographic.

Researchers found that NOC could imitate human voice by increasing pressure in the air sacs, so much that one could see the whale's head bulge a little as it talked. "The human voice appears to be very difficult for a cetacean to mimic," Ridgway said, National Geographic reports.