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Thursday, July 28, 2011

Dolphins have double sonar

It’s well known that dolphins use echolocation to navigate.  Recently, Josefin Starkhammer of Lund University and her colleagues from the National Marine Mammal Foundation in San Diego have discovered that dolphins are twice as capable as previously thought.  The researchers found that dolphins can generate two sound projections at once.

Echolocating dolphins emit high frequency sounds (ultrasounds) from organs within their foreheads.  These sound beams bounce of any objects (sea floor, predator, prey etc.) in their path and the resulting echo is interpreted by the animal’s brain. Although researchers knew that dolphins had two sound producing organs, it was assumed that only one was functional at a time.  Either both organs can function simultaneously, or some other process within the dolphins’ heads is dividing up single pulses.  In either case, more than one signal is leaving the dolphins’ heads.

Why send out two pulses?  As Starkhammer explains:
The beam projections have different frequencies and can be sent in different directions. The advantage is probably that the dolphin can locate the object more precisely.