The Wandering Soul PsyOp tape of Vienam
Helicopters were used to broadcast Vietnamese voices pretending to be from beyond the grave. They called on their "descendents" in the Vietcong to defect, to cease fighting. This campaign played the sounds and messages all night in order to spook the superstitious enemy. Despite eventually realizing that they were hearing a recording beamed from a helicopter, the enemy gunners could not help but fear that their souls would some day end up moaning and wailing in a similar fashion after death.