A Voice in the Fitting Room of a Clothing Store

It wasn't at night, but I'll tell it anyway, since it happened at work and it was really strange. I work in a clothing store, in a mall, and one time when I came to work in the morning, I started changing in the fitting room and then I hear a human voice next to me, like someone is standing there trying things on and talking, clearly, but not loudly. I went quiet and decided to listen, then after a minute I peeked out of the fitting room, still not dressed, and there was no one. I got dressed, walked around the whole store, but found no one, my colleagues came about 20 minutes after these events. Some say they feel the presence of something in the store. Out of the corner of my eye I sometimes notice movement myself (or maybe it just seems so), but I can't find anyone. So that's the story, anon.