NEW YORK — The seeds of Denver’s stunning Super Bowl self-destruction were planted during Wednesday’s practice when coach John Fox decided to turn down the speakers that simulate crowd noise because “it’s not an away game.”A silent snap count would have been so much better because Seattle’s famed 12th Man showed up on Denver’s first play from scrimmage and helped ruin whatever great game plan offensive coordinator Adam Gase and Peyton Manning had come up with.Instead of thwarting the Seahawks’ stingy secondary and stout front seven, the Broncos fell apart.MetLife Stadium might not have been as loud as CenturyLink Field, but it was plenty spirited as the start of all Super Bowls are and when Manning lined up in the shotgun and called for the ball from his 14-yard line, his center couldn’t hear the cadence.Manny Ramirez crouched still and just as Manning stepped up to reset the play, Ramirez’s snap sailed into the north end zone, where running back Knowshon Moreno smothered it for a safety.“None of us heard the snap count,” Ramirez said. “I thought I did and when I snapped it, I guess Peyton was actually trying to walk up to me at the time. I’m not 100 percent sure.