I actually remember a history teacher from back in my days at high school, talking about some of the speeches (in regards to the hype and getting everyone riled up). One thing I clearly remember from that class was the comments made about the speaker system (I can't provide any links so I guess this is only hearsay). According to the teacher, the speakers had special loose louvers on the front that were designed to CREATE distortion, esp at the loud bits. The idea being to make it harder to understand and the masses tended to follow along with the loyal supporters up front (plus, distortion gets you angry? ).
Like I said, can't prove it, but I vividly remember that for some reason.