Bullshit, louder, BULLSHIT, bullshit

I am an effects actor in a Halloween ghost tour. My location was in an enclosed office with frosted windows that I would make shadows and press my face onto, maniacal laughing, etc. On down time, I would record for possible voices. This one came through on my final night. I was alone in the office, no tours were nearby nor were any other actors close enough to be heard through the walls and so close to the recorder. So who are these people?