One hour mp3 of a 19hz sin wave also known as "infrasound" and has ties to "ghosts" and other supernatural events. Play at a barely audible volume during a horror game and induce dread into your players.
The MP3 may appear "blank" but it isn't the sound is supposed to be below human hearing and right at about the range of a low tiger roar. If played very loud you should hear it "thud" rappidly. Adjust the volume to just right under where you can hear it for maximum effect.
Infrasound has been known to cause feelings of awe or fear in humans. Since it is not consciously perceived, it can make people feel vaguely that supernatural events are taking place. ~Wikipedia