I’m only pitching in on this because the thread has been running for a couple of days with no uptake.
Surely the use of the human voice as “ammo” must be most definitely defined as the speaker systems employed by enemy forces broadcasting endless moral sapping messages to our troops in the trenches on the front lines in Asia. “you are going to get killed” “is it worth it?” “Think of your family” etc Also Lord Haw Haw in WW2.
Anyone who doubts that the human voice can sap moral should look at these for examples. Plus I suggest they never met my first wife!