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

We assumed that if they heard enough CCR they would come to appreciate American culture and stop fighting. Mistakes were made.