September 8, 2011
Dolphin Communication Similar To Humans
Researchers from Aarhus University have discovered that dolphin "talk" is similar to how humans communicate.
"When we or animals are whistling, the tune is defined by the resonance frequency of some air cavity," Peter Madsen, study leader from the Department of Biological Sciences at Aarhus University, said in a statement to Daily Tech. "The problem is that when dolphins dive, their air cavities are compressed due to the increasing ambient pressure, which means they would produce a higher and higher pitch the deeper they dive if they actually whistle."
The team found that dolphins produce sound using tissue vibrations comparable to how human vocal folds work.
The researchers digitized and analyzed recordings of a 12-year-old male bottle nose dolphins in 1977. They found that a dolphin breathes in a "heliox" mixture that consists of 80 percent helium and 20 percent oxygen.
The researchers said this combination of gases would make humans sound like Donald Duck because it has a sound speed that is 1.75 times higher than normal air.
"We found that the dolphin does not change pitch when it is producing sound in heliox, which means that its pitch is not defined by the size of its nasal air cavities, and hence that it is not whistling," Madsen told Daily Tech's Tiffany Kaiser.
"Rather, it makes sound by making connective tissue in the nose vibrate at the frequency it wishes to produce by adjusting the muscular tension and air flow over the tissue. That is the same way that we humans make sound with our vocal cords to speak."
The team says that this findings applies to all toothed whales because they have the same nasal anatomy as dolphins.
Engineer John Stuart and Speak Dolphin organization member Jack Kassewitz said that dolphins have a complex system of social interactions that includes sounds like chirps and clicks.
"There is strong evidence that dolphins are able to 'see' with sound, much like humans use ultrasound to see an unborn child in the mother's womb," Kassewitz said in a press release.
"The CymaScope provides our first glimpse into what the dolphins might be 'seeing' with their sounds. I believe that people around the world would love the opportunity to speak with a dolphin. And I feel certain that dolphins would love the chance to speak with us -- if for no other reason than self-preservation."
The study was published in the Royal Society Biology Letters.
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