Scientists analyse the 'alien song' coming from the Mariana Trench - and finally reveal the truth about the mysterious noises

The Mariana Trench is 1 of the astir mysterious places connected Earth.

Measuring astir 7 miles (37,000ft) deep, the trench sits connected the level of the Pacific Ocean and is truthful hard to scope that conscionable a fistful of radical person ventured down there.

So it's nary astonishment that antithetic sounds coming from the Mariana Trench sparked fears of an alien penetration erstwhile they were first recorded backmost successful 2014.

Lasting betwixt 2.5 and 3.5 seconds, the noises were dubbed 'biotwangs', yet their root was unknown.

Ten years later, scientists from the National Oceanic and Atmospheric Administration (NOAA) person reanalysed the sounds - and judge they've yet revealed the truth.

The eerie noises were archetypal recorded successful 2014 by underwater gliders, which were being utilized to transportation retired acoustic surveys of the trench.

Lasting betwixt 2.5 and 3.5 seconds, the five-part sounds included heavy moans astatine frequencies arsenic debased arsenic 38 hertz and a finale that pushed arsenic precocious arsenic 8,000 hertz.

Researchers were initially baffled by the noises.

However, successful 2016, a squad from Oregon State University (OSU) suggested that they could beryllium a caller benignant of antecedently unheard baleen whale call.

Speaking astatine the time, Sharon Nieukirk, elder module probe adjunct successful marine bioacoustics astatine Oregon State, said: 'It's precise distinct, with each these brainsick parts.

'The low-frequency moaning portion is emblematic of baleen whales, and it's that benignant of twangy dependable that makes it truly unique. 

'We don't find galore caller baleen whale calls.'

Now, scientists person reanalysed the noises utilizing a operation of ocular and acoustic survey information – and their findings suggest that the OSU squad wasn't acold off.

Rather than being produced by baleen whales, the caller survey suggests that Bryde's whales are responsible.

In a survey published successful the Frontiers successful Marine Science journal, the team, led by Dr Ann Allen, explained: 'It was assumed to beryllium produced by a baleen whale, but without ocular verification it was intolerable to delegate a species.

'Using a operation of ocular and acoustic survey information collected successful the Mariana Archipelago, we determined that Biotwangs are produced by Bryde's whales.'

Bryde's whales tin beryllium recovered astir the satellite successful warm, temperate oceans including the Atlantic, Indian, and Pacific.

The researchers spotted 10 of the whales swimming successful the area, and adjacent recorded 9 making the distinctive noises.

However, to beryllium these whales were so the source, the squad turned to artificial intelligence.

'We utilized a operation of manual and instrumentality learning annotation methods to observe Biotwangs successful our extended humanities passive acoustic monitoring datasets collected crossed the cardinal and occidental North Pacific,' they explained successful the study.

'We identified a accordant seasonal beingness of Biotwangs successful the Mariana Archipelago and to the eastbound astatine Wake Island, with occasional occurrence arsenic acold distant arsenic the Northwestern Hawaiian Islands and adjacent the equator (Howland Island).'

The squad inactive doesn't cognize wherefore the whales' calls are truthful unusual, oregon wherefore they're being made successful the archetypal place. 

However, speaking to Popular Science, Dr Allen suggested: 'It's imaginable that they usage the biotwang arsenic a interaction call, a benignant of "Marco Polo" of the ocean. 

'But we request much accusation earlier we tin accidental for sure.'