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What’s that sound? Many scientists have come up with curious answers to explain some of the mysterious noises found in nature, while others are discovering strange new sounds from the extremes of the Earth and outer space.
Here are 11 strange sounds that deserve to be heard.
First up: They call it the "Bloop"
The BloopSlide 2 of 23
Over the past 70 years, the world’s oceans have emerged as a valuable global listening device, first by networks of underwater microphones scanning for enemy submarines during the Cold War, and in more recent decades, by scientists studying the oceans and the internal structure of the Earth.
One of the most famous and powerful underwater sound events, known as Bloop, was recorded by the U.S. National Oceanic and Atmospheric Administration (NOAA) in 1997. The Bloop event lasted for about 1 minute and rose in frequency from a low rumble. It was detected by underwater microphones more than 3,000 miles (5,000 kilometers) away and was much louder than the noises made by any known animal.
The rough location of the event that caused Bloop is in the sea near the Antarctic Circle, and NOAA now thinks that Bloop was caused by the sound of massive icebergs "calving," or splitting, from the end of Antarctic glaciers and falling into the sea.
Several other distinctive underwater sound events have been identified and named by NOAA: a weird cooing sound dubbed "Julia" that was likely caused by an iceberg running into the seafloor, an event known as "Train" (because it sounded like train wheels against a track) that scientists think likely originated in Antarctica's Ross Sea, and a scratchy noise dubbed "Upsweep," which likely originates in the Pacific and has been picked up by hydrophones seasonally since 1991.
Next up: A fishy chorusSlide 3 of 23
Aquatic choirsSlide 4 of 23
Scientists in Australia report that many different species of fish join in a mass chorus with their fellows at dawn and dusk, in much the same way as many birds.
The researchers, from Curtin University in Perth, recorded vocal fish songs off the coast of Port Headland in Western Australia for 18 months, reported New Scientist. They were able to make recordings of seven distinct choirs of fish, including overlapping foghorn calls made by Black Jewelfish and the "ba ba ba" sounds repeated by chorusing batfish.
Most of the noises recorded by the scientists are just a single fish repeating the same call over and over. But, when two or more fish of the same kind can hear each other, often over a large distance underwater, they began to overlap their calls in a synchronous pattern. The researchers noted that sound plays an important role in many fish behaviors, such as breeding, feeding and territorial disputes.
Next up: A lonely whaleSlide 5 of 23
The Loneliest WhaleSlide 6 of 23
The Loneliest Whale
The world's "loneliest whale" was first recorded in 1989 by an American military network listening for nuclear submarines. It's been identified as a blue whale by the pattern of its calls, but it seems to have a uniquely high voice, with the main notes at a frequency of 52 hertz — a low bass note to human ears.
Most blue whales speak in voices at frequencies between 10 and 40 hertz. This is how the Loneliest Whale picked up its lonesome eponym, because scientists and the media speculated that it was unable to communicate with all the other blue whales.
It's possible that "Sad Moby" may be a hybrid whale, with one parent from a different whale species, which could cause a different body shape and a different call. But, recent research suggests the difference between the Loneliest Whale and all the rest of the blue whales in the world may be not such a big social challenge after all.
The researchers say many idiosyncratic whale calls have been detected, and some studies suggest that groups of whales living in particular regions have distinct "dialects" of whale song that often differ in frequency.
Later recordings have also found that the Loneliest Whale is now changing its tune — the whale's call has been getting deeper for several years and now registers around 47 hertz. So, maybe it has cheered up a bit?
Next up: Deep-sea soundsSlide 7 of 23
Deep noiseSlide 8 of 23