Infrasound: It can be Murder on the Dance Floor
We all know how a good bass line feels when you’re out throwing some shapes in a night club. Sometimes the bass is so low, not only can you hear it, you feel it too. These days you can buy CDs where the bass line is so low the CD comes with the warning: “The ultimate competition, showin’ off your system and having a good time doing it disc… you might even blow something up!” Rock on. Here’s a great description of someone’s experience with a stereo system with incredible bass (stay with me here, it’s all relevant):
“I stick the plugs in, and he hits the burp button, a red switch on the centre console. It’s difficult to describe what happens next. The noise sounds like ‘BRRRROONNNNNKKKK!’ The vehicle vibrates like a jackhammer, but much lower and deeper. I feel air blowing the back of my hair, and my body starts to rise out of the seat. My pant legs are flapping. Everything in the car is rattling like crazy, and I realize my vision is blurred as my face pulls back taut against my skull. The only reaction left is to laugh out loud. I look over at Billy E gripping the steering wheel, squinting and grinning maniacally. He lets up on the button and the chaos stops.
“‘If you’re drinking a Coke, your throat will shut.’ I’m amazed I can actually hear his voice. ‘It’s like being under water. Your ears don’t ring they’re just muted. After a day, everything opens up again,’ he says.
If these are some of the effects bass can have on you, what else can it do?
The normal limit of human hearing is 20Hz (Hertz) (don’t worry, I’m not about to blind you with science that I barely understand myself). Below 20Hz, sound turns into infrasound. Anything lower than that becomes harder to hear but you may start to feel it instead. Infrasound can cover long distances and get around obstacles without losing too much energy, so it remains pretty potent for a long time.
Infrasound can have quite devastating effects on people. Walt Disney accidentally wrecked an audience when he unwittingly produced a cartoon sound effect which, at 12 Hz, made everyone present nauseous for several days.
Infrasound can also induce feelings of sickness, anxiety and the sensation that you are being watched. It can affect your eyesight too, making you see things out of the corner of your eye. The phenomenon has been used as an explanation for the feelings people get in haunted houses and also as a cause of low level poltergeist activity.
High enough doses of infrasound can incapacitate people and, apparently, even kill under certain conditions. During the 2009 G20 summit in Pittsburgh, police used sound cannons against protestors. Just think, if the police had got the frequency right they could have had a rave on their hands instead of a riot.
Infrasound can be caused by many things, both natural and manmade. Elephants, whales and even giraffes have been found to create infrasound, as have diesel engines, wind turbines and sub woofers (the kind that are big enough to blow your head off).
So, if you’re in a haunted house and you feel as if you’re being watched, you might want to check outside to make sure the workmen haven’t got their diesel generator going full bore before calling in the ghost busters.
©Nicola Kirk and http://www.nicolakirk.wordpress.com 2010