Let’s say you’ve just moved into a gorgeous old house. It’s everything you’ve ever dreamed of: elaborate Gothic architecture, towering turrets, and an extra-long dining room table for you to sit at, ominously alone. The only thing is that there are … stories about this place. Dark stories. And one day, when you’re down in the cellar, you feel a presence surrounding you. You look up, and for just a second, you see someone standing there — and then they disappear. But this isn’t a ghost story. It’s the terrifying tale of how you have an expensive problem with your plumbing.
Here’s what we’re talking about. The story starts in the 1980s when IT lecturer Vic Tandy was working at a company that made medical equipment. There was one laboratory at the office that had a certain reputation. People just felt like they were being watched in there, and every once in awhile, somebody would say they actually saw something in the room with them. Vic never really gave the stories any credence — until they happened to him.
One night (let’s just go ahead and say it was dark and stormy), he was working in the lab when he began to feel it. He broke out in a cold sweat. And then, just on the periphery of his vision, a dark shape that nearly coalesced into a human figure, but disappeared when he looked directly at it. We certainly don’t blame him for bringing a sword to work the very next day.
Okay, so the sword wasn’t for fighting ghosts. Vic was an avid fencer, and he intended to fix his foil using one of the clamps in the laboratory. But as soon as he secured the blade, it began to vibrate, and suddenly everything fell into place. Vic calculated that the sword was responding to a vibration in the air of about 19 Hz — just outside of the range of human hearing. He then pinpointed the source of the sound to an industrial fan, and as soon as the fan was flipped off, the ominous presence disappeared. Nobody ever saw that shape again, either, probably because the low vibrations were causing the eyeballs to buzz in their sockets.
So what does it all mean? Basically, if you’re experiencing haunting symptoms like an unshakeable feeling of unease, a mysterious presence that disappears when you look at it, and swords vibrating of their own accord, you might have a mechanical problem somewhere in the house. It might be an old piece of machinery (like Vic Tandy’s industrial fan) or something screwy in the plumbing or ventilation system filling your home with an inaudible sound. Once plates start hovering around or the walls start bleeding, then we’d say you might have a real ghost issue.
So what is it about sounds around the area of 19 Hz that disturb us so badly? It might just be our subconscious mind trying to get our attention. The human ear starts picking up sounds at around the 20 Hz mark, but there are other ways that we can detect sound — stand next to a subwoofer at a concert, and you’ll feel the sound in your chest more than your ears. So when there’s a sound that we sense but can’t hear, the body might be thrown into a panic. And that panic might have kept us safe when we were living on the savannah.
See, there are a lot of animals that make noise in the infrasound range. Alligators, rhinoceroses, tigers, and elephants are all known to bellow infrasound frequencies loud enough to be heard for miles — and if you can’t hear them, you might still feel them. If you didn’t notice, all of those animals are ones that you don’t necessarily want to get too close to. So that specter you’ve seen wandering your hallways? It might just be your brain thinking there’s a tiger nearby.