Sonic weapon

Marines will use a bizarre new "Secret Scream" gun to disable people.

The actual sound used is a recording of a baby's scream played backwards.
"For most people, even if they plug their ears, it will produce the equivalent of an instant migraine," said Woody Norris, chairman of American Technology Corporation, the Californian company that has produced the weapon.
"It will knock some people to their knees."

The gun was created through secret Pentagon research:

A secret division in the Pentagon has been financing research on futuristic weapons for more than 15 years.