they ain’t afraid of no ghosts Low-frequency infrasound (below 20 Hz) can raise cortisol levels in saliva and increase irritability. Ireland's Kinnitty Castle is reportedly the home of many ghosts, including the Phantom Monk of Kinnitty Credit: Public domain The next time you walk into a purportedly “haunted” house and sense a ghostly presence, consider that those feelings might be due to vibrating pipes, mechanical or climate control systems, rumbling from traffic, or wind turbines, rather than anything paranormal. That’s the conclusion of a new paper published in the journal Frontiers in Behavioral Neuroscience. All of those are sources of infrasound . Scientists have long sought to find logical explanations for alleged hauntings. In 2003, for instance, University of Hertfordshire psychologist Richard Wiseman conducted two studies that investigated the psychological mechanisms underlying supposed “ghostly” activity.…