Why were loudspeakers used during the Vietnam War?

Question

I was watching a movie that took place in Vietnam War and saw that they put large loudspeakers on tanks, boats and even on helicopters. On another TV Series, Generation Kill that took place in Iraq War, they don’t have such things. Soldiers usually sing by themselves.

I’m wondering:

* what was the purpose of loudspeakers?
* why they don’t use it anymore?

In: 219

Answer 1

I was a cadet at the United States Air Force Academy back in the mid eighties. The summer after your freshman year you had to take a ‘class’ called SERE: survival, evasion, resistance, escape. One part of the training is a simulated POW camp. At night they would play loud music, same shit over and over again, to make us sleep deprived and easier to control.