As you are all aware, ghost sightings have been around for centuries. Every person who has reported a ghost sighting has always claimed to feel a cold chilling feeling and dread and depression, along with the actual spotting of the ghost. But there has never been any hardcore proof or scientific evidence of such a thing being able to happen...until now. Scientists have found that these feelings are actually cause by extremely low frequency sound waves called infrasound that cause one to feel emotions like depression, dread, fear, and others. It is so low in frequency that we can not consciously hear it, but our ears still sense it. Not only is it everywhere in nature (volcanoes, earthquakes, even tigers), but it can be caused by things such as a malfunctioning ventilation shaft, which is one reason why these "haunted" buildings happen in the first place.
But what about the actual sighting of ghosts? Same thing: infrasound. At a specific frequency, it vibrates and resonates perfectly with your eyeball, shaking the eye ever so slightly, giving what is called a smeared look. This causes the vision to respond in weird ways, such as thinking you saw a ghost walk by you and such.
THE TRUTH HATH BEEN REVEALED!
For more in depth detail and proofs through experiments, check out the link below: