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At first, muffled (听不太清的)conversations made researchers at a San Diego aquarium puzzled, but when a diver thought he was being told to get “out” of the water they realized the conversations were coming from a white whale.
Noc was about one year old when he was caught off the Pacific coast of Canada. He was kept in an open-ocean pen (围栏) at the US National Marine Mammal Foundation in San Diego, California. After seven years at the Foundation, he began, automatically, to make unusual sounds, a report in the latest issue of the journal, Current Biology, said.
“We thought of the whale' s vocalizations(发出的声音) as an attempt to imitate humans. Whale vocalizations often sounded as if two people were talking just out of the range of our understanding,” the authors said. “ 'These conversations' were heard several times before we finally realized the whale was the source.” The researchers realized it was Noc when a diver surfaced and asked, “Who told me to get out?” It was then that they realized the word “out”, which was repeated several times, had come from Noc. Later, his speech-like sounds were recorded in the air and underwater.
Noc started making the sounds after seven years in the open-ocean pen, and continued making them for another four years. He died five years ago. Researchers have now analyzed the sound recordings. It was the first time that sound recordings had shown how such sounds imitated speech and were different from the usual calls of the species.
The speech-like sounds were lower than normal whale sounds and much closer to those of the human voice. Also, whales talk to each other by blowing air through their noses, rather than using a larynx(喉), as people do.
“We don't claim that our whale was a good imitator compared to such well-known imitators as parrots,” the researchers said. “However, the behavior we observed is an example of vocal learning by the white whale. It seems that Noc's close association with humans played a role in how often and how well he employed his human voice.”
cC中，物质的含量A%和C%随温度的变化曲线如图所示，下列说法正确的是 （两个答案）（ ）