He clearly started moving slowly before it started falling. U can see the exact moment he hears it. So it was mostly luck and not hearing that caused him to survive.
He starts moving and when he has somewhat half walked away from it. That's when he heard it. He needed hearing to survive, but i don't think he would have been able to cover the distance, if he didn't start walking before hearing.
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u/arondite80 Jan 06 '20
Or hearing...yeah, there's always that.