A white whale which learnt to imitate the voices of humans may have been trying to make contact, scientists believe.
The male named Noc had a distinctly human-like voice, much to the surprise of scientists who previously thought whales typically produce sounds in a manner that is wholly different from humans.
Noc died five years ago after 30 years of living amongst dolphins and other white whales and being in contact with humans at the National Marine Mammal Foundation based in San Diego in California.
Sam Ridgway, who led the study, said: 'Our observations suggest that the whale had to modify its vocal mechanics in order to make the speech-like sounds.
Mr Ridgway and his colleagues first began to notice some unusual sounds in the vicinity of the whale and dolphin enclosure which was described a sounding as though two people were conversing in the distance in 1984.
The sounds were traced back to Noc after a diver surfaced from the whale enclosure to ask his colleagues an odd question 'Who told me to get out?'
Although there has been other anecdotal reports of whales sounding like humans before, in this case Ridgway’s team wanted to capture some real evidence by recording Noc over the years.
The team built a special underwater listening platform to try and hear more 'voices'.
It revealed a rhythm similar to human speech and fundamental frequencies several octaves lower than typical whale sounds, much closer to that of the human voice.
Mr Ridgway said: '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.'
He said it was all the more remarkable because whales make sounds via their nasal tract, not in the larynx as humans do.
To make those human-like sounds, Noc had to vary the pressure in his nasal tract while making other muscular adjustments and inflating the vestibular sac in his blowhole.
In other words, they say, it wasn't easy.
The study 'Spontaneous human speech mimicry by a cetacean' are published in the latest issue of Current Biology.
The whale called 'NOC' was the youngest of three that had been collected at Churchill, Manitoba, Canada in August of 1977.
At times, the speech-like sounds were heard from a distance when no humans were nearby, however most episodes were observed when humans were nearby on the surface or underwater.
