(CNN) — Australian researchers plan to release an audio recording Wednesday of an underwater sound that they say could possibly be related to the final moments of missing Malaysia Airlines Flight 370.
It’s a long shot, but researchers at Curtin University near Perth, Australia, have been studying records from underwater listening devices, including those meant to monitor for signs of underwater nuclear explosions, in an effort to help find the missing plane.
“One signal has been detected on several receivers that could be related to the crash,” said Alec Duncan with the university’s Centre for Marine Science and Technology (CMST).
Researchers have been analyzing the very low frequency sound for weeks to see if it was “the impact of the aircraft on the water or the implosion of parts of the aircraft as it sank,” Duncan said. “But (the source of the noise) is just as likely to be a natural event.”
Members of the media scramble to speak with Azharuddin Abdul Rahman, director general of Malaysia’s Civil Aviation Department, at a hotel in Kuala Lumpur, Malaysia, on Tuesday, May 27. Data from communications between satellites and missing Malaysia Airlines Flight 370 was released Tuesday, more than two months after relatives of passengers say they requested that it be made public. The flight has been missing since March 8.
This photo illustration shows a journalist looking on the data communication logs from British satellite operator Inmarsat. Malaysian authorities have published the 47-page document containing hundreds of lines of communication logs between the jetliner and Inmarsat’s satellite system.
Relatives of Chinese passengers who were on Malaysia Airlines Flight 370 listen to part of the audio communications between Flight 370′s cockpit and air traffic controllers during a meeting with Malaysian officials Wednesday, April 30, in Beijing.
An autonomous underwater vehicle is brought back aboard the Australian ship Ocean Shield after a search mission for the flight Saturday, April 19, in the southern Indian Ocean.
A Royal Malaysian Air Force plane takes off from an airbase near Perth, Australia, to help in the search on Thursday, April 17.
Operators aboard the Australian ship Ocean Shield move Bluefin-21, the U.S. Navy’s autonomous underwater vehicle, into position to search for the jet on Monday, April 14.
A member of the Royal New Zealand Air Force looks out of a window while searching for debris off the coast of western Australia on Sunday, April 13.
British Royal Navy sailors aboard the vessel HMS Echo take part in the search for the jet on April 13.
Crew members aboard the Echo watch a smaller boat that’s part of the British search effort on April 13.
The Echo moves through the waters of the southern Indian Ocean.
A map provided Saturday, April 12, details efforts to find the missing jet.
Chinese navy personnel head out on a boat to the Royal Australian Navy ship HMAS Success on Wednesday, April 9.
A Royal Australian Air Force AP-3C Orion, on a mission to drop sonar buoys to assist in the search, flies past the Australian vessel Ocean Shield on April 9.
A relative of a missing passenger cries at a vigil in Beijing on Tuesday, April 8.
A member of the Royal Australian Air Force walks toward a plane that just arrived in Perth on April 8.
Australian Defense Force divers scan the water for debris Monday, April 7, in the southern Indian Ocean.
A towed pinger locator is readied to be deployed April 7 off the deck of the Australian vessel Ocean Shield.
Capt. Mark Matthews of the U.S. Navy talks to reporters in Perth about the search on April 7.
A member of the search operation points to a map outlining search areas during a news conference April 7 in Perth.
A U.S. Navy airplane takes off from Perth to assist in the search on April 7.
A member of the Royal New Zealand Air Force looks at a flare in the Indian Ocean during search operations on Friday, April 4.
Members of the Royal New Zealand Air Force monitor data April 4 on board an aircraft during search operations.
A relative of a Flight 370 passenger watches television in a Beijing hotel as he awaits new information about the missing plane on Thursday, April 3.
Another relative of a Flight 370 passenger waits for updates in Beijing on Wednesday, April 2. Many families have criticized the Malaysian government’s handling of information in the plane’s disappearance.
A member of the Japanese coast guard points to a flight position data screen while searching for debris from the missing jet on Tuesday, April 1.
Kojiro Tanaka, head of the Japanese coast guard search mission, explains the efforts en route to the search zone April 1.
A woman prepares for an event in honor of those aboard Flight 370 on Sunday, March 30, in Kuala Lumpur, Malaysia.
An underwater search-surveying vehicle sits on the wharf in Perth, ready to be fitted to a ship to aid in the search for the jet.
A girl in Kuala Lumpur writes a note during a ceremony for the missing passengers on March 30.
A teary-eyed woman listens from the back as other relatives of Flight 370 passengers speak to reporters March 30 in Subang Jaya, Malaysia. Dozens of anguished Chinese relatives demanded that Malaysia provide answers to the fate of those on board.
An object floating in the southern Indian Ocean is seen from a Royal New Zealand Air Force P-3K2 Orion aircraft searching for the missing jet on Saturday, March 29. Ships participating in the search retrieved new debris Saturday, but no objects linked to the missing plane, according to Australian authorities.
A Royal New Zealand Air Force member launches a GPS marker buoy over the southern Indian Ocean on March 29.
The sole representative for the families of Flight 370 passengers leaves a conference at a Beijing hotel on Friday, March 28, after other relatives left en masse to protest the Malaysian government’s response to their questions.
A member of the Royal Australian Air Force is silhouetted against the southern Indian Ocean during the search for the missing jet on Thursday, March 27.
Flight Lt. Jayson Nichols looks at a map aboard a Royal Australian Air Force aircraft during a search on March 27.
People in Kuala Lumpur light candles during a ceremony held for the missing flight’s passengers on March 27.
Crew members of the Chinese icebreaking ship Xuelong scan the Indian Ocean during a search for the missing jet on Wednesday, March 26.
People work at a console at the British satellite company Inmarsat on Tuesday, March 25, in London.
The mother of a passenger who was on Malaysia Airlines Flight 370 cries at her home in Medan, Indonesia, on March 25.
Australian Defense Minister David Johnston speaks to the media March 25 about the search for the missing jet.
A family member of a missing passenger reacts after hearing the latest news March 25 in Kuala Lumpur.
Angry relatives of those aboard Malaysia Airlines Flight 370 react in Beijing on Monday, March 24, after hearing that the plane went down over the southern Indian Ocean, according to analysis of satellite data.
Grieving relatives of missing passengers leave a hotel in Beijing on March 24.
Malaysian Prime Minister Najib Razak, center, delivers a statement about the flight March 24 in Kuala Lumpur. Razak’s announcement came after the airline sent a text message to relatives saying it “deeply regrets that we have to assume beyond any reasonable doubt that MH 370 has been lost and that none of those onboard survived.”
Relatives of the missing passengers hold a candlelight vigil in Beijing on March 24.
A member of the Royal Australian Air Force looks out an aircraft during a search for the missing jet March 24.
A woman reads messages for missing passengers at a shopping mall in Kuala Lumpur on March 24.
Flight Lt. Josh Williams of the Royal Australian Air Force operates the controls of an AP-3C Orion on Sunday, March 23, after searching the southern Indian Ocean.
Ground crew members wave to a Japanese Maritime Defense Force patrol plane as it leaves the Royal Malaysian Air Force base in Subang, Malaysia, on Sunday, March 23. The plane was heading to Australia to join a search-and-rescue operation.
A passenger views a weather map in the departures terminal of Kuala Lumpur International Airport on Saturday, March 22.
A Chinese satellite captured this image, released on March 22, of a floating object in the Indian Ocean, according to China’s State Administration of Science. It is a possible lead in the search for the missing plane. Surveillance planes are looking for two objects spotted by satellite imagery in remote, treacherous waters more than 1,400 miles from the west coast of Australia.
A member of the Royal Australian Air Force looks down at the Norwegian merchant ship Hoegh St. Petersburg, which took part in search operations Friday, March 21.
The Royal Australian Air Force’s Neville Dawson, left, goes over the search area with Brittany Sharpe aboard an AP-3C Orion some 2,500 kilometers (about 1,500 miles) southwest of Perth, Australia, over the Indian Ocean on March 21.
Satellite imagery provided by the Australian Maritime Safety Authority on Thursday, March 20, shows debris in the southern Indian Ocean that could be from Flight 370. The announcement by Australian officials that they had spotted something raised hopes of a breakthrough in the frustrating search.
A closer look at the satellite shot of possible debris from Malaysia Airlines Flight 370.
Another satellite shot provided by the Australian Maritime Safety Authority shows possible debris from the flight.
A closer look at the satellite shot of possible debris.
The Australian Maritime Safety Authority’s John Young speaks to the media in Canberra, Australia, on March 20 about satellite imagery.
A distraught relative of a missing passenger breaks down while talking to reporters at Kuala Lumpur International Airport on Wednesday, March 19.
A relative of missing passengers waits for a news briefing by officials in Beijing on Tuesday, March 18.
A relative of a missing passenger tells reporters in Beijing about a hunger strike to protest authorities’ handling of information about the missing jet.
A member of Indonesia’s National Search and Rescue Agency joins in a search for the missing plane in the Andaman
Sea area around the northern tip of Indonesia’s Sumatra on Monday, March 17.
Relatives of missing passengers watch a news program about the missing plane as they await information at a hotel ballroom in Beijing on March 17.
Malaysian Transportation Minister Hishamuddin Hussein, center, shows maps of the search area at a hotel next to the Kuala Lumpur International Airport on March 17.
U.S. Navy crew members assist in search-and-rescue operations Sunday, March 16, in the Indian Ocean.
Indonesian personnel watch over high seas during a search operation in the Andaman Sea on Saturday, March 15.
A foam plane, which has personalized messages for the missing flight’s passengers, is seen at a viewing gallery March 15 at Kuala Lumpur International Airport.
A member of the Malaysian navy makes a call as his ship approaches a Chinese coast guard ship in the South China Sea on March 15.
A Indonesian ship heads to the Andaman Sea during a search operation near the tip of Sumatra, Indonesia, on March 15.
Elementary school students pray for the missing passengers during class in Medan, Indonesia, on March 15.
Col. Vu Duc Long of the Vietnam air force fields reporters’ questions at an air base in Ho Chi Minh City, Vietnam, after a search operation on Friday, March 14.
Members of the Chinese navy continue search operations on Thursday, March 13. The search area for Flight 370 has grown wider. After starting in the sea between Malaysia and Vietnam, the plane’s last confirmed location, efforts are expanding west into the Indian Ocean.
A Vietnamese military official looks out an aircraft window during search operations March 13.
Malaysian air force members look for debris on March 13 near Kuala Lumpur.
A relative of a missing passenger watches TV at a Beijing hotel as she waits for the latest news March 13.
A member of the Indonesian National Search and Rescue Agency scans the horizon in the Strait of Malacca on Wednesday, March 12.
Relatives of missing passengers wait for the latest news at a hotel in Beijing on March 12.
Journalists raise their hands to ask questions during a news conference in Sepang on March 12.
Indonesian air force officers in Medan, Indonesia, examine a map of the Strait of Malacca on March 12.
A member of the Vietnamese air force checks a map while searching for the missing plane on Tuesday, March 11.
Iranians Pouri Nourmohammadi, second left, and Delavar Seyed Mohammad Reza, far right, were identified by Interpol as the two men who used stolen passports to board the flight. But there’s no evidence to suggest either was connected to any terrorist organizations, according to Malaysian investigators. Malaysian police believe Nourmohammadi was trying to emigrate to Germany using the stolen Austrian passport.
An Indonesian navy crew member scans an area of the South China Sea bordering Indonesia, Malaysia and Thailand on Monday, March 10.
Vietnam air force Col. Le Huu Hanh is reflected on the navigation control panel of a plane that is part of the search operation over the South China Sea on March 10.
Relatives of the missing flight’s passengers wait in a Beijing hotel room on March 10.
A U.S. Navy Seahawk helicopter lands aboard the USS Pinckney to change crews before returning to search for the missing plane Sunday, March 9, in the Gulf of Thailand.
Members of the Fo Guang Shan rescue team offer a special prayer March 9 at Kuala Lumpur International Airport.
A handout picture provided by the Malaysian Maritime Enforcement Agency shows personnel checking a radar screen during search-and-rescue operations March 9.
Italian tourist Luigi Maraldi, who reported his passport stolen in August, shows his current passport during a news conference at a police station in Phuket island, Thailand, on March 9. Two passengers on the missing Malaysia Airlines flight were reportedly traveling on stolen passports belonging to Maraldi and an Austrian citizen whose papers were stolen two years ago.
Hugh Dunleavy, commercial director of Malaysia Airlines, speaks to journalists March 9 at a Beijing hotel where relatives and friends of the missing flight’s passengers are staying.
Vietnamese air force crew stand in front of a plane at Tan Son Nhat airport in Ho Chi Minh City on March 9 before heading out to the area between Vietnam and Malaysia where the airliner vanished.
Buddhist monks at Kuala Lumpur International Airport offer a special prayer for the missing passengers on March 9.
The Chinese navy warship Jinggangshan prepares to leave Zhanjiang Port early on March 9 to assist in search-and-rescue operations for the missing Malaysia Airlines flight. The Jinggangshan, an amphibious landing ship, is loaded with lifesaving equipment, underwater detection devices and supplies of oil, water and food.
Members of a Chinese emergency response team board a rescue vessel at the port of Sanya in China’s Hainan province on March 9. The vessel is carrying 12 divers and will rendezvous with another rescue vessel on its way to the area where contact was lost with Malaysia Airlines Flight 370.
The rescue vessel sets out from Sanya in the South China Sea.
A family member of missing passengers is mobbed by journalists at Kuala Lumpur International Airport on Saturday, March 8.
A Vietnamese air force plane found traces of oil that authorities had suspected to be from the missing Malaysia Airlines plane, the Vietnamese government online newspaper reported March 8. However, a sample from the slick showed it was bunker oil, typically used to power large cargo ships, Malaysia’s state news agency, Bernama, reported on March 10.
Malaysian Prime Minister Najib Razak, center, arrives to meet family members of missing passengers at the reception center at Kuala Lumpur International Airport on March 8.
Malaysia Airlines official Joshua Law Kok Hwa, center, speaks to reporters in Beijing on March 8.
A relative of two missing passengers reacts at their home in Kuala Lumpur on March 8.
Wang Yue, director of marketing of Malaysia Airlines in China, reads a company statement during a news conference at the Metro Park Lido Hotel in Beijing on March 8.
Chinese police at the Beijing airport stand beside the arrival board showing delayed Flight 370 in red on March 8.
A woman asks a staff member at the Beijing airport for more information on the missing flight.
A Malaysian man who says he has relatives on board the missing plane talks to journalists at the Beijing airport on March 8.
Passengers walk past a Malaysia Airlines sign on March 8 at Kuala Lumpur International Airport.
Malaysia Airlines Group CEO Ahmad Juahari Yahya, front, speaks during a news conference on March 8 at a hotel in Sepang. “We deeply regret that we have lost all contacts” with the jet, he said.
Photos: The search for Malaysia Airlines Flight 370
Official: MH370 is not in ping area
Officials: Flight 370 not in search area
Low frequency signals can travel thousands of kilometers through water under favorable circumstances, at about 1.5 kilometers per second, Duncan said. But “at the moment (the sound) appears to be inconsistent with other data about the aircraft position,” he said.
That’s because researchers at Curtin University believe the sound came from an area thousands of kilometers to the northwest of the current search area in the southern Indian Ocean. And even then, they haven’t been able to pinpoint the source.
Duncan says his team has calculated an “uncertainty box” for the signal’s origin. It’s area that stretches some 4,000 kilometers in length from southeast to northwest, and spans some 200 to 300 kilometers in width. And he says the center is south of the tip of India.
The university plans to release more data about the sound on Wednesday, including an audio clip captured by one of the listening devices, off of Perth. Duncan says his team has sped up the recording 10 times to make it audible to the human ear.
Searching in the right place?
The search for the missing Malaysia Airlines flight continues to focus along an arc hundreds of kilometers long, the area where investigators believe the Boeing 777 ran out of fuel, about 1,000 miles off the coast of Western Australia.
Martin Dolan, the chief commissioner with the Australian Transport Safety Bureau (ATSB), the organization leading the search into MH370 at the request of Malaysia, says an international team of experts continues to review the analysis of Inmarsat satellite data and aircraft performance.
In a television exclusive, Dolan told CNN’s “Erin Burnett OutFront” he remains confident the final resting place of MH370 is somewhere along that arc, the so-called “partial handshake” with the satellite:
“We’ve seen all the data. We’ve seen all the calculations. We are reviewing the calculations and are also developing our own model to cross check and verify that information,” Dolan told Burnett.
When asked last week about the underwater sound being analyzed by the team at Curtin University, along with Geoscience Australia, a government agency, Dolan was skeptical.
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“We think that those detections may have been interesting from the point of view of the direction they came, but other characteristics make it unlikely that they are associated with MH370,” he said. The ATSB first referenced these signals in a document posted on its website on May 26.
Listening below the surface
As was the case with the Inmarsat satellite — a communications satellite whose data was analyzed by Malaysia Airlines MH370 investigators as a navigational aide — the analysis of the underwater signals involves the use of technology for a different purpose than its original intent.
One of the devices, operated by Curtin University and located some 20 kilometers off Perth, is designed to listen to whales and other marine life. The other is for signs of underwater nuclear explosions, one of 11 operated worldwide by the U.N.-chartered Comprehensive Test Ban Treaty Organization (CTBTO) as part of the International Monitoring System.
Early in the search for Malaysia Flight 370, the United Nations reported it had not detected any explosions or plane crashes on land or water from its sensors around the globe. But the recent efforts involve pairing CTBTO data with other sources to see what can be gleaned, officials said.
“One can always be hopeful,” said Mark Prior, a seismic acoustic analyst with the CTBTO.
The CTBTO’s hydro-acoustic stations detect low frequency sound in the 0-100 Hz range, and can’t detect black box “pings” in the 30-40 kHz range, officials said. “It’s possible (to detect a plane crash), but the circumstances that would allow it would have to be very particular,” said Prior.
Prior said some of those circumstances might include a sloping sea bed. Another possible scenario: the origin of the sound would need to be near the listening device.
The CTBTO’s system near Cape Leeuwin, the southwestern-most point of Australia, regularly captures signals of ice breaking noise from Antarctica and seismic activity from Indonesia, he said. “There are other scenarios that would allow (the hydrophones to detect a crash). But it’s not certain if there was an impact we would detect it,” Prior said.
Attempts were made following the 2009 crash of Air France 447 in the southern Atlantic Ocean to see if underwater listening devices had detected the plane’s impact. No data could be found.
Years later, after the plane was located, CTBTO again checked its data, and still was not able to identify signals related to the crash.
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