Answer:
Step-by-step explanation:
There are a few conditions as mentioned: "you walked down an empty hallway and heard the echo of your footsteps." So first thing is as you walk, your shoes touch the floor and make noises. Those are sounds of your footsteps. You are in a hallway so the sounds are trapped within the hallway. It is empty so there is nothing like people who would block and absorb the sounds. With sounds bouncing around walls and floor of the hallway, they bounce back to the source: you. That is when you hear the echo of your footsteps.