Mythbusters fright night

Humans can generally sense sounds at frequencies between 20 and 20,000 cycles per second , or hertz (Hz)—although this range shrinks as a person ages. Prolonged exposure to loud noises within the audible range have long been known to cause hearing loss over time.

One study has suggested that infrasound may cause feelings of awe or fear in humans. It has also been suggested that since it is not consciously perceived, it may make people feel vaguely that odd or supernatural events are taking place.

Infrasound can only be blocked by a solid earplug , either custom fitted to the ear canal or sealed with jelly to generate an air-tight seal.

Subwoofers are speakers designed to reproduce these frequencies, adding realism to movies, video games and other media. By connecting a variable-frequency sine-wave oscillator to a self-amplified subwoofer, you can produce infrasound . Turn on the subwoofer and oscillator.

According to recent studies, your brain learns and expresses fear at a certain brainwave frequency, and changing the frequency can change the feeling. Researchers found that the brainwave frequency of fear is four cycles per second, or 4 hertz .

The most dangerous frequency is at the median alpha-rhythm frequencies of the brain: 7 hz . This is also the resonant frequency of the body’s organs.