Dolphin sonar or echolocation is one way that these marine mammals communicate with one another, but it is also their operative system to locate objects that are far away from them. They use this sonar or echolocation to ascertain the size, shape and speed of whatever it is they are looking for. Echolocation uses sound to locate or establish where an object is. Dolphin echolocation skills are so accurate that they can even figure out what they are viewing based simply on the object's density.
Water Conducts Sound
Water is an excellent conductor of sound -- and since dolphins live in water -- this works to their advantage. Dolphins have nasal sacs situated in their heads; and through these sacs they emit very fast clicking sounds that move through their rounded melon-shaped foreheads. The sound waves zoom through the water four and a half times faster than sound does through the air, then it rebounds off of the object and travels back to the dolphin for interpretation.
Dolphins do not have exposed ears like other animals. Their middle ear is concealed, so when sound or sonar waves are transmitted back to the dolphin, they are received through fat-filled pockets in the animal's lower jaw, instead of through an outer ear. Then auditory nerves transfer these messages to the dolphin's middle ear and brain, so that they can be interpreted.
Dolphins use their sonar or echolocation skills to hunt, to orient themselves and even to find lost baby dolphins or other members of their pod. Swedish researcher Dr. Josefin Starkhammar of Lund University in Sweden studies dolphins and says that "the beam projections have different frequencies and can be sent in different directions."
Double Sonar Thesis
Dr. Starkhammar's research has concluded that dolphins produce their sonar from two sound-producing organs -- and these two sound beams, used together -- are what enables them to echolocate objects. Previously, it was believed that dolphins only used one sound-producing organ. She believes this is what enables the marine animals to be so precise in their ability to locate objects.
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