The room where the echo arrived late

An original descriptive account of an invented empty sports hall.

The hall was empty except for a trolley of folded mats. Lines crossed the floor in several colours, making a network of games that nobody was playing. High windows held squares of grey sky. The light reached the centre of the room but seemed to stop before the corners.

I called to my brother, who had gone to find the caretaker. My voice returned from the far wall a moment after I had finished speaking. It sounded thinner on the way back, as though someone had repeated the words without quite understanding them. I decided not to call again.

Near the ceiling, a loose panel clicked at irregular intervals. Between the clicks, I could hear the small squeak of my trainer whenever I shifted my weight. I stood still. The room seemed to grow around the silence, and the door through which we had entered looked unexpectedly far away.

Then the trolley moved. Only a few centimetres: one wheel had turned on a slight slope. The mats settled with a soft sigh. I laughed too loudly at my own reaction, and the echo delivered the laugh back to me after the amusement had gone.

How does the writer create an uneasy atmosphere in the hall?