11.   The dull roar of helicopter rotors sent the streets into a panic.

12.   The dull roar of tires and banging of the hood over bumps eliminated any chance for conversation.

13.   When the hysteria finally settled down to a dull roar, Ponce signed autographs, shook hands and posed pretty for a barrage of cameras.

14.   The dull roar of circling Russian jets sent fighters at the camp into their dugouts.