Underwater sound recorders near Rottnest Island in Western Australia picked up the signal just after 1:30am (UTC) on March 8th, shortly after Malaysian Airlines Flight MH370 disappeared.
Now, scientists from Curtin University in Perth are investigating whether the sound could have been caused by the plane either hitting the water, or part of the aircraft imploding as it sunk into the Indian Ocean, as io9 reports.
But, more likely, it could also have been caused by a natural event such as a small earth tremor, Alec Duncan from Curtin University’s Centre for Marine Science and Technology told the Liam Ducey from the Sydney Morning Herald.
Duncan only gives around a 10% chance that the sound resulted from the plane hitting the water, although it’s hard to assess the possibility.
Interestingly, another underwater listening station in Western Australia picked up a correlating acoustic signal.
"Data from one of the [Rottnest] recorders showed a clear acoustic signal at a time that was reasonably consistent with other information relating to the disappearance of MH370," Dr Duncan told the Sydney Morning Herald.
"The crash of a large aircraft in the ocean would be a high energy event and expected to generate intense underwater sounds ... We sent the data to search authorities and I got a phone call at 3am in the morning so they were definitely interested in it."
But, before you get too excited, the proposed location of the sound doesn’t match the satellite “handshake” data transmitted from the aircraft, so there’s not too much to go on just yet.
The researchers are continuing to analyse the signal for further clues.