I missed it. And for some reason, I have Beck on (comes on after Breitbart) and he was talking about this - mentioned that every mike is different and it is on the speaker to find the sweet spot.
And did Donald try before cussing it out... dunno. Maybe this one was acting inconsistently. So many unknown details.
Nonsense. The sound guys are responsible for setting up a mic that works - notice how most of these events have two mics at the lectern. Helps if you want a stereo feed and really helps if one mic flakes out. Mics have very good matching across production lots, so if you have a set of them they work the same.
Anyone working in the pro sound business knows that you don't tell Jon Bon Jovi, or Bruce Springsteen, or Axl Rose that he needs to find the "sweet spot" of the mic you gave him. If the mic isn't good it just comes flying towards you and you damn well better have a roadie ready to run out with another one.
A speech mic on a lectern should be a piece of cake for a pro audio crew. I'd suspect sabotage myself if I heard the kind of bad audio Mr. Trump had to contend with.