A car backfiring, for instance, can set off an emotional response in a combat veteran if the loud noise becomes associated in his mind with a wartime experience.

比如，汽车爆胎会让退伍老兵产生情绪化的反应，只要他的脑子将这声巨响同战争中的某次经历联系在了一起。

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One resident, 30-year-old Rebecca Carbone, said she head a loud blast that "sounded like a car backfiring".

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The most common incidents -- the slam of a door, a car backfiring, a surprise tap on the shoulder -- can cause a panic reaction.

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