For example, occurrance of hearing a sound like loud door knocks without a source to locate it. Or seeing such things of tiny black scuttling objects scitter just out of the corner of your eyes a vanish without explaination.

The black objects could be shadow beings. The ones I have seen are fleeting shadows that I catch out of the corner of my eye for the most part. Although I have also looked directly at a shadow person, which occurred while standing in the middle of a cemetery. I have also seen them a couple of times in apartments I lived in. But it is rare to catch them like that - like I said, usually its just a quick glimpse as they move around.

And they can be different shapes and sizes too, not necessarily a normal human shape.

Noises are interesting, but tough to decipher because there are so many natural causes for them. Houses make a lot of noise that you normally dont pay much attention to, unless its very quiet or you are listening for them. And once I kept hearing this really weird static-like noise. Turns out it was one of my son's toys that was on "demo mode" so it would play a noise every once in a while.

Interesting, thanks for sharing!