Infrasound is sound with a frequency too low to be heard by the human ear. The study of such sound waves is sometimes referred to as infrasonics, covering sounds beneath the lowest limits of human hearing (20 hertz) down to 0.001 hertz. This frequency range is utilized by seismographs for monitoring earthquakes. Infrasound is characterized by an ability to cover long distances and get around obstacles with little dissipation. Although we can't hear it, it does have an effect on the body, causing 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. Haunted houses often utilise this to manipulate people into feeling things they ordinarily wouldn't, as do some composers. Church organs also create infrasound. I feel that this accounts for a lot of so called "religious experiences" in churches.