Dolphins do not whistle as previously thought. Instead, they "talk" like humans, according to a new study.

A dolphin takes part in an aquatic football match at the Hefei Aquarium in Hefei, capital of east China's Anhui Province, July 8, 2010.?[File Photo]

Dolphins use their noses to produce a different kind of tonal sound, just like humans do when speaking, said Peter Madsen, the lead author of the study published in Royal Society Biology Letters.

Madsen studied how dolphins communicate by digitizing recordings made in 1977 of a 12-year-old male dolphin, which was made to breathe a mixture of helium and oxygen called heliox.

Scientists said humans breathing in a heliox sound like Donald Duck.

According to Livescience.com, the heliox was meant to mimic conditions during a deep dive since it causes a shift up in frequency. When breathing in heliox , the dolphin, however, continued to make the same sounds with the same frequency.

"That means that dolphins do not actually whistle, but make sound by making connective tissue in the nose vibrate at the frequency they wish to produce by adjusting the muscular tension and air flow over the tissue," Madsen said, "This is the same way that we humans make sound with our vocal cords to speak."

But "It does not mean that they talk like humans, only that they communicate with sound made in the same way,"said Madsen.

Dolphins make actual whistlings in performances when they are trained, just like humans sometimes whistle for fun.

But Madsen doesn't "think they do it in the wild, because they have evolved a much more effective way to make the same sound."