Australian Ocean Shield officials have confirmed that a “stable, distinct and clear signal” has been detected in the Indian Ocean, significantly reducing the search area for Malaysian Airlines flight 370.

The recorded signals are “consistent with the description of a Flight Data Recorder,” Air Chief Marshal and search head Angus Houston said in a Wednesday lunchtime briefing from the Joint Agency Coordination Centre in Perth.

“Hopefully in a matter of days we will be able to find something on the bottom to indicate that this is the final resting place of MH370,” Mr Houston said.

This is the second occasion underwater pulses have been detected in the same area after signals were recorded twice on Saturday.

The signals were first analysed by the Australian Joint Acoustic Analysis Centre, in Nowra NSW.

“What we’re picking up is a great lead,” Mr Houston said, “I’m now optimistic that we will find the aircraft or what is left of the aircraft in the not-too-distant future. But we haven’t found it yet.”

“I believe we are searching in the right area,” he said.

Two acoustic signals were detected over the weekend, it was revealed on Monday.

Black box ‘ping’ locations. Map: AMSA

Mr Houston displayed a map (above) that showed the first black box “pings”, picked up on Saturday afternoon and evening, were near the final radar “handshake” the plane made with satellites.

The re-detections occurred on Tuesday afternoon and evening.

“We are looking for transmissions that are probably weaker than they would be earlier on,” Mr Houston said.

It is 33 days since the plane went missing en route from Kuala Lumpur to Beijing – three days beyond the life of the black box beacon’s battery. But they are known to last several days longer.

Mr Houston said there were no plans to send more ships and pinger locators to the northern search area, which was being combed in tighter patterns, because it was crucial to keep the waters as quiet as possible.

Two thrusters were operating at the back of the Ocean Shield to propel it through the waves, but everything else had been turned off to optimise the operation of the pinger locator.

He said he was optimistic plane wreckage would be found “in the not too distant future”.

But photographic evidence taken from a submersible would be required before the area was declared the final resting place of MH370.

“We need to make hay while the sun shines. We need all the data we can,” he said, referring to the weakening black box battery.

Mr Houston said the Chinese-led effort in the southern part of the search zone had not picked up any further audio signals since a detection was reported on Sunday.

A map of the search area for the missing Malaysia Airlines jet. Map: AMSA

-with AAP