Thursday, 15 September 2011
* covert insertion and extraction of CIA personnel* covert trasportation of sensitive cargo* light aircraft* turboprop transport planes* jet airliners* helicopters
A new study has revealed that dolphins use tissue vibrations to talk to each other, a process very similar to the way humans communicate.
Scientists found that whistle like sounds of dolphins are produced by tissue vibrations analogous to the operation of vocal folds by humans and some other land-based animals, MSNBC reported.
"When we or animals are whistling, the tune is defined by the resonance frequency of some air cavity," said lead author Peter Madsen of the Department of Biological Sciences at Aarhus University.
According to the study published in Royal Society Biology Letters, Madsen's team studied how dolphins communicate by digitizing and reanalyzing recordings of a 12-year-old male bottlenose dolphin made in 1977.
They found that the dolphin breathed in a 'heliox', a mixture of 80 percent helium and 20 percent oxygen, in which the pitch of the tune can be 1.74 times higher than in 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 said.
The animal adjusts the muscular tension and air flow over the connective tissue in its nose exactly as humans make sound with their vocal cords to speak, he added.
Researchers believe their findings can enable them to figure out the meaning of dolphin calls.
Scientists suggest that this process can be applied to all toothed whales with similar nasal anatomy.