Ears are for hearing -- everyone knows that. But for a creature called the Cuvier's beaked whale, hearing starts in the throat, a new study found.  The observation might help explain how all whales hear. The work might also help scientists understand how animals are affected by underwater sonar  . This sonar, used by some ships, sends out sound waves to locate underwater objects.  The Cuvier's beaked whale is a so-called toothed whale. Toothed whales dive deep into the ocean in search of food. As the whales hunt, they produce sounds that reach objects and then return to the whales. This allows the animals to "see" the shape, size, and location of objects, even when they're 1,000 meters under the sea, where it is totally dark.  To better understand how the whale hears, researchers from San Diego State University in California took X-rays of two Cuvier's beaked whales. The whales had died and washed up on the beach.  Ted Cranford and his colleagues used the images to make a computer model of a Cuvier's beaked whale's head. Then, they modeled the process of sound traveling through the head.  The researchers knew that some sounds get to the ears of a toothed whale through a structure called "the window for sound". Found on the lower jaw, this structure is very thin on the outside and has a large pad   of fat on the inside.  When the researchers used their computer model to work out how sound waves travel in the whale's head, they were surprised to find that sounds coming from right in front of the whale actually travel under the animal's jaw. From there, sound waves move through the throat, into a hole in the back of the jaw, and finally to the pad of fat near the animal's ears.  Cranford guesses that other types of whales may hear through their throats. Further testing is needed to be sure. Eventually, the insight into how whales hear might explain whether sonar testing by military ships is causing the animals to wind up on beaches. Researchers took X-rays of two Cuvier's beaked whales in order to   _  .
find out why they had died and washed up on the beach make a computer model of a Cuvier's beaked whale's head make sure that sound travels through the head know more about the way the whale hears