I work as an officer at a really old prison. I've been there for over sixteen years and have seen many strange things. The facility was built in the 1930's and it has a large, old barn there.
Anyway, I was doing my rounds that night and went to check the barn. I was interested in recording EVP's at the time so I figured I would try to capture some in the barn. I was alone at the time and started my voice recorder. No EVP's were heard on playback. I tried several times, on different nights. Still, no luck. Well, I almost gave up.
Then, late one night, I sat alone and began again. I said, "hello" and then I heard on the recorder, a female, or a child's voice answer me back with a long, "hello". This was a very, very clear response. I was surprised to hear a female or child, however. Being that the prison is for adult males. My guess is that the barn is older than the prison itself. And it does appear much older than the rest of the facility. Could this have been the voice of a family member that lived here years before the prison was built? Who knows?
Anyway, after I recorded that voice, I got the idea to play it back while going back into the barn the next night. So, I began my rounds and settled into the barn after checking the perimeter. My theory was that if I played back the voice, I might get more activity. And boy, was I right!
Sitting there, I began to play back the voice. I did this by putting it on a loop, or continuous play. Then I heard a loud, Bam Bam Bam! My hairs stood up and goosebumps, the size of quarters, covered my whole body from the sudden fear! So, I hightailed it out quick! Needless to say, I didn't do that again. Be careful what you ask for, right?
So, I fear no human being, but sometimes when an entity can make sounds or move things, it's hard to remain calm. Especially when you can't defend yourself from something invisible.