When it comes to things like ghosts and poltergeists and spirits, you can put me in the “skeptical” pile. I’m a believer in science and think that just about anything can be explained with a little research. Here’s an example of what I’m talking about. Have you ever suddenly felt uneasy like there was a presence you couldn’t quite identify? All you know is that you became scared and weirded out. A ghost? Maybe not. Scientists have noted something called the “fear frequency,” which starts at 18.9 Hz, just below the lowest range of human hearing. We can’t hear these sounds at this frequency but our bodies can definitely feel it. And when we do—and when these sounds are loud enough—they may trigger feelings of anxiety and fear. No ghosts. Just really, really deep bass.