Mysterious sound from the deep 11,000m below the Pacific Ocean

The mysterious sound that American scientists recorded near the bottom of the 10,971 m deep in the Pacific Ocean may be the whale's call that had never been heard before.

Called "Western Pacific Biotwang" , the newly discovered call may come from spearhead whales, horned whales, according to the sound collection team. The call includes a wide range of sounds spanning between 38 and 8,000 Hz while the human hearing is 20 - 20,000 Hz, the Live Science reported on December 17.

"The call is very special, " said Sharon Nieukirk, senior research assistant at the oceanic biology department at the University of Oregon, USA. "The low-frequency sound is often seen in horned whales and the nasal voice itself makes a really unique cry."

The position of the scientists who obtained the strange sound was 10,971m deep in the bottom of the Mariana basin.(Photo: Google Earth).

The cry is captured by an automatic diving robot, which can dive as deep as 1,000 meters below the surface of the water. Nieukirk and colleagues collected audio data in the fall of 2014 and 2015 in the waters east of Guam, around the Mariana bottom, the deepest place in the Pacific.

The call consists of 5 segments, each lasting 3.5 seconds, recorded continuously in spring and autumn. The team hopes other scientists can recognize the sound in other data sources, allowing them to confirm the source of the sound. In the magazine's description of the American Acoustics Association, Nieukirk and his colleagues suggest that the cry belongs to the spearhead whale.

Due to the complex structure, frequency and metal tone of the cries, the researchers deduce it is most similar to the characteristic cry created by a group of dwarf whales in northeastern Australia. They also emphasized that there are some key whales in the survey area but not much information about their behavior, especially the sound they emit.

Researchers will continue to learn about the sound. Most horny whales use a special cry during the mating season to call their partners, but this cry appears year-round so it can serve many complex functions.