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How Dolphins SEE

The dolphin's echolocation beam was directed at a submerged man and the echo captured by a hydrophone system. The echo signal was sent to sound imaging laboratory who used it to create what-the-dolphin saw image of man.

Researchers in the USA and UK have made a significant breakthrough by capturing an echolocation image of man from dolphin. The resulting picture captured following enhancement techniques is faint, but key features are revealed with more detail when compared to previous images.

Team leader Jack Kassewitz of said, “This is the first time we have captured a what-the-dolphin-saw image of a man. We employed a similar technique in 2012 to capture a dolphin’s echolocation picture of a flowerpot and several other submersed plastic objects but the present research has confirmed that result and so much more.”

The research took place at the Dolphin Discovery Center in Puerto Aventuras, Mexico. The submerged man, Jim McDonough, used a weight belt and exhaled most of the air in his lungs to overcome his natural buoyancy. He then made himself as flat against the bottom of a research pool by arranging himself by some shelves. It was decided not to use any breathing apparatus to ensure that there would

be no bubbles. Bubbles would adversely affect the results of the experiment, therefore, the whole event had to be accomplished within a single breath.

With Jim in position the female research dolphin, Amaya, was tasked to echolocate upon the man. Most of the resulting echo from his body was reflected back to Amaya but one of water’s sonic properties is similar to that of air and causes sounds (echoes) diffract in many directions simultaneously. One theoretical implication of this property is that when a dolphin sees an object with its echolocation sense it may be possible for all other dolphins nearby also receive the image or “see” what she does through her sound-vision system.

The dolphin’s echo signal was recorded using high specification audio equipment by the Speak Dolphin team. The recording was then sent via email to the CymaScope laboratory in the UK for analysis. The CymaScope can create what the dolphin saw images from sound. The instrument transcribes sonic periodicities to water wavelet periodicties, in other words the sound sample is imprinted onto a water membrane. The Acoustic physics researcher injected the click train into the

CymaScope, while running the camera in video mode, he saw a fleeting shape on the water’s surface and saw something entirely unexpected, the faint outline of a man.

Kassewitz said, “I was astonished when I received the faint image of Jim’s whole body because I had no idea that Amaya had been echolocating on him during her approach – before the dolphin trainer had given her the signal to begin echolocating. I called John in the UK and we discussed the image in detail. Later, he sent me a computer enhanced version that revealed several details not easily seen in the raw image, such as the weight belt worn by Jim. Having demonstrated that the CymaScope can capture what-the-dolphinsaw images our research infers that dolphins can at least see the full silhouette of an object with their echolocation sound sense, but the fact that we can just make out the weight belt worn by Jim in our what-the-dolphin-saw image suggests that dolphins can see surface features too. The dolphin has had around fifty million years to evolve its echolocation sense whereas marine biologists have studied the physiology of cetaceans for only around five decades, and I have worked with John Stuart Reid for barely five years. Even so, our recent success has left us all speechless. We now think it is safe to speculate that dolphins may employ a “sono-pictorial” form of language, a language of pictures that they share with each other. If that proves to be true an exciting future lies ahead for inter species communications.”


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