[awjr]

> Sonar is not a weapon; it's a sensor system intended to discover enemy submarines.

When a friend was working on sonar software they had extremely rigorous safety controls in place when working in the same room as a test rig. Pings could kill you. At a minimum you would shatter your ear drum.

[MrZongle2]

A passenger jet engine could do the same, yet that too isn't classified as a weapon.

[awjr]

The medium is different. Sound travels 4 times further and faster in water than air. Dolphins even use sound to stun their prey.

Sound in water is a more effective weapon. The ping of a sonar is a weapon within the medium of water. A quick search: "There are no noise-cancelling headphones to stop the U.S. Navy's 235-decibel pressure waves of unbearable pinging and metallic shrieking. At 200 Db, the vibrations can rupture your lungs, and above 210 Db, the lethal noise can bore straight through your brain until it haemorrhages that delicate tissue. If you're not deaf after this devastating sonar blast, you're dead."