Military warships use sonar for tracking underwater targets. But how dangerous is it to humans?

Australian naval personnel have sustained minor injuries to their ears after being subjected to sonar pulses from a Chinese warship. The incident occurred while the group of divers were fixing their ship’s propellers in international waters, within Japan’s exclusive economic zone. Active sonar systems — the technology at the heart of the incident — emit sound pulses and listen for the echoes, whereas passive ones only listen. Military warships commonly use sonar for navigating deep water, avoiding submerged obstacles and tracking underwater targets, such as torpedoes and naval mines. These systems mirror techniques used by some marine animals, and are…