China News: The Australian government revealed that its naval divers suffered minor injuries last Tuesday, which may have been the result of a sonar pulse from a Chinese navy ship. Divers were clearing fishing nets from the propeller of HMAS Toowoomba in international waters off the coast of Japan. According to a statement from Deputy Prime Minister Richard Marles, despite HMAS Toowoomba communicating with internationally recognized signals, the Chinese vessel approached the Australian ship and activated its sonar. This forced the Australian divers to exit the water.
The incident prompted a response from the Australian government, which described the incident as unsafe and unprofessional. Meanwhile, the question arises that what is sonar pulse and what kind of injury can sonar cause to divers? What is sonar? Light doesn’t travel smoothly underwater—even in clear water, you can probably see only a few tens of meters. However, sound travels very well and far under water. This is because water is much denser than air, and can therefore react faster and better to acoustic pressure waves—sound waves. Because of these properties, ships use sonar to navigate through the ocean and ‘see’ underwater.
What is the meaning of the word sonar?
The word ‘sonar’ means sound navigation and ranging. The sonar device sends short acoustic (sound) pulses or pings, and then analyzes the echo. Based on the timing, amplitude, phase, and direction of the echo received by the instrument, you can tell what’s under the water – the sea floor, canyon walls, coral, fish, and of course ships and submarines. Most vessels—from small, private yachts to large commercial tankers—use sonar. However, compared to your off-the-shelf sonars used to find fish, naval sonars are more robust.
What effect does Senar have on divers?
What effect does sonar have on divers? This is a difficult topic to study, because you don’t want to intentionally expose humans to harmful levels of sound. However, there are accounts of various navies coming into contact with it. There have also been studies on what humans can hear underwater, with or without a neoprene suit, hood, or helmet. We don’t hear well underwater – no surprise, since we evolved to live on land. When this happens you will hear a sonar sound (medium to high pitch noise) under the water and you will know you have come into contact with it.
When it comes to naval sonars, human divers rate the sound at levels ranging from ”unpleasant to severe” at levels around 150 dB per 1 Pa (decibels relative to a reference pressure of one micropascal, the standard reference for underwater sound). Evaluated as. This would probably be, very roughly, 10 km away from a military sonar.
May even experience deafness
Note that we cannot compare hearing sound underwater with sound received through air, as there are too many physical differences between the two. The human tolerance limit is about 1 µPa per 180dB, which would be about 500 meters from military sonar. At such levels, humans may experience dizziness, temporary memory loss and effects on concentration, or temporary deafness. We do not know the level of trauma the Australian divers suffered, but their injuries are described as minor.
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