Yesm the sniffling is distracting. They probably put a super sensitive mic on him. lol.
COuld be the mic, and it also could be the air conditioning in the arena...that can make folks “”sniff”
They’re using a standard audio process called compression that limits loud sounds and emphasizes quiet sounds. It’s a way of keeping the sound at an average level. Unfortunately it will emphasize sniffles. Someone should have coached Trump to turn his head away from the mic when sniffling. Or they should have pumped him full of sudafed.