Terrifying reality of what happens if you accidentally hear an active submarine sonar while underwater

Sonar technology is the bees knees when it comes to exploring, searching or mapping large bodies of water and has often been the unsung hero in huge cases.

It's what was used by search crews attempting to find the doomed Titan sub, by researchers who found a 30ft-long mass lurking 500ft beneath Loch Ness and by the team trying to track down missing pilot Amelia Earhart and her plane.

And everyone kind of presumes that sonar - which is short for Sound Navigation and Ranging - is completely safe and somewhat inaudible to humans, even if a swimmer accidentally ended up in its path.

But the reality of the situation is a lot more dangerous.

Basically, active sonar transducers emit acoustic signals or pulses of sound into the water and hope that it runs into any objects that may be of interest.

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If this is the case, then the sound sent out will bounce back off the item, returning an 'echo' to the system which can then calculate the strength of the signal, while giving the operators an idea of what it may be.

Whereas passive sonar simply means listening for the sound made by vessels, which is probably why we all have such a false sense of security surrounding the technology.

We use sound to detect things below the surface as light doesn't travel very well underwater, while ships also use sonar to help them navigate the waves and to effectively 'see' what is in their path.

Most boats are equipped with active sonar technology these days, but obviously its power pales in comparison to that of huge navy ships.

A gang of Australian divers found this out the hard way back in November last year, as they were right in the firing line of the sound pulses when a Chinese vessel blasted its sonar.

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The country's defence minister, Richard Marles, said the HMAS Toowoomba paused while it was in international waters after its propellers ended up tied up in fishing nets.

The divers were sent out to remedy the problem, but China's PLA-N destroyer (DDG-139) ship was also operating close-by and, despite being warned an operation was underway, it 'approached at a closer range'.

Marles said: "Soon after, it was detected operating its hull-mounted sonar in a manner that posed a risk to the safety of the Australian divers who were forced to exit the water.

"The divers sustained minor injuries, likely due to being subjected to the sonar pulses from the Chinese destroyer."

When high levels of active sonar are used, it can cause dizziness, disorientation, temporary memory issues, concentration problems and temporary hearing loss.

In serious cases, it can even cause organ damage.

Marine bioacoustics scientist told the West Australian that active sonar pulses can rupture the lungs, while ones which exceed 210dB can cause fatal brain haemorrhaging.

Divers would likely hear a mid-to-high pitch sound while underwater when the active sonar is emitted, cluing them into the fact that they may be in serious danger.

So if your ears ever start ringing while you've gone for a dip in the ocean, maybe you should resurface. Fast.

Topics: Technology, Health, News, Science, Australia

Olivia Burke

Olivia is a journalist at LADbible Group with more than five years of experience and has worked for a number of top publishers, including News UK. She also enjoys writing food reviews (as well as the eating part). She is a stereotypical reality TV addict, but still finds time for a serious documentary.

@livburke_