At first, they couldn't tell where the sound was coming from. Researchers at the National Marine Mammal Foundation kept hearing what sounded like a muffled conversation, as if two people were talking just around a corner. It was only when a diver climbed out of the enclosure holding a male beluga whale and said, "Who told me to get out?" that they realized the whale himself was making the speech-like noises. It was 1984, and the beluga, called NOC, had been living at the research center for seven years. Belugas are known for being noisy. But they usually stick with a standard whale repertoire of squeals, whistles and clicks. As for NOC, it seemed that after all his years of hearing human speech, both from trainers and researchers above the water and from divers talking on underwater equipment, he had developed a decent impression: https://dl.dropbox.com/u/37173439/beluga.mp3 I like to imagine the whale is griping to one of its whale friends. "So I was working with the trainer today, and he was all like DURP DE DOO, BLER BLER BLER, BLOOOOOR DE DUM DUM! Pfft." By inserting tubes into their beluga mimic's nasal cavity (or, more accurately, convincing the beluga to allow them to insert tubes into his nasal cavity), the researchers learned exactly how he was manipulating pressure in his nasal tract to produce the strange sound. They describe their results in Current Biology. But even though they discovered how the whale was performing his signature trick, they could never know exactly why. As NOC matured, he retired his human impression. Five years ago, the beluga died. His legacy will be the lasting knowledge that to whales, humans sound just like the Swedish Chef.
Sam Ridgway, Donald Carder, Michelle Jeffries, & Mark Todd (2012). Spontaneous human speech mimicry by a cetacean Current Biology, 22 (20) : 10.1016/j.cub.2012.08.044
Image: Jason Pier (not the same beluga whale). Audio: Current Biology, Ridgway et al.