A captive white whale that made unusual mumbling sounds when he was in the presence of people may have been trying to mimic his human companions, scientists have found.
An acoustic analysis of the sounds made by a beluga whale called NOC has revealed remarkable similarities to human speech patterns, indicating that the whale was trying to “reach out” to his human captors, scientists believe.
Although there are anecdotal accounts of whales sounding like “ children shouting from a distance”, this is the first time that scientists have produced hard evidence that they are capable of trying to imitate human speech.
One of the first indications that NOC was able to sound like a human was when a diver swimming alongside him in his pen came to the surface and asked his colleagues “who told me to get out”?
NOC, who died five years ago, was about a year old when he was captured off the Pacific coast of Canada in 1977. He was kept in an open-ocean pen at the US National Marine Mammal Foundation in San Diego, California, where he took part in scientific research on cetacean acoustics.
Sam Ridgway, a researcher at the foundation, analysed the archived sound recordings made when NOC was alive and compared them to the sounds made by the human voice, such as the speech patterns and multiple harmonics of spoken words.
The comparison revealed a remarkable similarity that was even more remarkable given that whales vocalise between themselves by blowing air through their noses rather than the larynx in the throat, which is how humans make vocal sounds.
“Our observations suggest that the whale had to modify its vocal mechanics in order to make the speech-like sounds. Such obvious effort suggests motivation for contact,” Dr Ridgway said.
The sound recordings revealed that NOC’s vocalisations were pitched at fundamental frequencies several octaves lower than normal whale sounds, and much closer to those of the human voice. NOC’s sounds also had a rhythm similar to human speech patterns.
“Whale voice prints were similar to human voice and unlike the whale’s usual sounds. The sounds we heard were clearly an example of vocal learning by the white whale,” Dr Ridgway said.
It was in 1984, after seven years in captivity at the San Diego foundation, that NOC started spontaneously to make the unusual sounds which the scientists soon interpreted as him trying to mimic the people around him.
“Whale vocalisations often sounded as if two people were conversing in the distance just out of range of our understanding. These ‘conversations’ were heard several times before the whale was identified as the source,” Dr Ridgway said.
“The whale was recognised as the source of the speech-like sounds when a diver surfaced outside this whale’s enclosure and asked ‘who told me to get out?’ Our observations led us to conclude that the ‘out’ which was repeated several times came from NOC,” he said.
It appears that NOC made extraordinary efforts to make contact with his human captors given that he had to vary the pressure in his nasal tract to mimic the voices he heard around him, while as the same time inflating his vestibular sac, a fold of skin found near his blowhole, which is not normally inflated in such an extreme way.
However, within four years of learning to sound human-like, NOC gave up mimicking the people around him and went back to sounding like a whale, emitting echolocation pulses, high-pitched whistles and an assortment of noises variously described as “squawks, rasps, yelps and barks”.
It appears that NOC’s attempt at communicating with his captors was a brief childish flirtation that he soon grew out of. Or perhaps he thought it was a lost cause.
The study is published in the journal Current Biology.