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Every one hundredth of a second counts in the Olympic Games, especially when it comes to track and field events. Due to lag in sound-traveling time, runners in the farthest lane have a disadvantage because they are last to hear the start signal.
In the past, the "gun" gives runners in the closer lanes a distinct leg-up in the race. This year, however, the Olympics committee is using an electronic gun that makes no noise at all. Instead, it's wired to speakers directly behind each runner, ensuring all runners hear the starting gun at the same time.