Man, could you imagine how upset folks would be if they spawned, and then just blinked back into the tower? Never having even heard a shot? They'd be dead before the sound arrived, lol!
Deer hunting, I've unfortunately had rounds pass by me close enough to hear them whiz past on three separate occasions. The sound of the gun firing definitely comes later...
Game-wise, I almost suspect that it would be easier to locate your adversary if the sound of his gun firing was delayed (assuming he missed). I say that because the round zipping past (or impacting) certainly gets your attention, and then the sound of the gun pinpoints the direction of the threat.