Have you ever stuck your head under the water in a pool, bathtub, river or lake? You would think things would be very quiet, but you can actually hear all kinds of sounds, although they aren’t nearly as loud.
Turns out that even seven miles deep in the ocean — that’s almost 37,000 feet below the surface — there are still many sounds.
Scientists recently wrote about lowering a specially built microphone into the Mariana Trench, the deepest part of the Pacific Ocean. Called a hydrophone, the device had to be strong enough to handle the tremendous pressure of 16,000 pounds per square inch because all of that water was pressing down on the device. In comparison, in your house the pressure is only about 15 psi.
"You would think that the deepest part of the ocean would be one of the quietest places on Earth," said Robert Dziak, one of the project’s researchers. "Yet there really is almost constant noise from both natural and man-made sources.”
One of the most common noises heard was earthquakes. The hyrdophone also picked up the moans of baleen whales, the sounds created by a typhoon stirring up the surface and ships cruising past.
The recordings will help future researchers to see if there has been an increase in human-caused noise deep underwater.
Because they sent the hydrophone so deep into the ocean, it took more than six hours for it to reach the bottom.
"It is akin to sending a deep-space probe to the outer solar system," Dziak said. "We're sending out a deep-ocean probe to the unknown reaches of inner space."
— Brett French
Gazette Outdoors editor