A white whale has been observed imitating the voices of human beings, despite the fact that its vocal system is completely different.
The sounds, several octaves lower than those usually made by the whale, were so human-like that one diver surfaced from the whale enclosure, asking his colleagues: "Who told me to get out?"
The team quickly realized that the sounds came from a white whale called NOC, which had lived among dolphins and other white whales and had often been in the presence of humans.
The team recorded the whale's sounds to reveal a rhythm similar to human speech and fundamental frequencies several octaves lower than typical whale sounds, much closer to that of the human voice.
NOC eventually grew out of his talkativeness when he matured, after about four years.
"Whale voice prints were similar to human voice and unlike the whale's usual sounds," says Sam Ridgway of the National Marine Mammal Foundation. "The sounds we heard were clearly an example of vocal learning by the white whale."
It's a remarkable achievement, because whales make sounds via their nasal tract, rather than in the larynx as humans do. To make the sounds, NOC had to vary the pressure in his nasal tract while making other muscular adjustments and inflating the vestibular sac in his blowhole, the researchers found. In other words, says the team, it wasn't easy.
"Our observations suggest that the whale had to modify its vocal mechanics in order to make the speech-like sounds," says Ridgway. "Such obvious effort suggests motivation for contact."