Infrasound: The Silent Creepy Sound of the Horror Movies

Sitting comfy with the best friend in the dark theatre, you watch the character navigating the lonely path through the forest. There was nothing scary about walking along a lonely road, but when the low sounds float out through the speakers surrounding the theatre, you somehow fear for the safety of the character while technically sitting on the edge of the seat holding your breath.

Did the above scenario seem familiar? As stereotypical as it may sound, the horror movie directors (and other genre movie music directors) knows the power of sound/music in their movies, and they capitalise on it every chance they got. Films like The Shining did instil some level of fear in the audience with its clever use of sounds and music.

The sounds of silence

Filmmakers now employ another ingenious way to increase the scare factor in the movies. They do this through the introduction of infrasound. Infrasound involves the use of low-frequency bass waves or vibrations to induce fear, a low frequency which can cause anxiety.

Our ears usually have a range of frequencies it can respond to, and the field is between 20Hz to 20,000 Hz. Though under the optimum condition and with the use of earphones, a human can hear 1.5Hz. A frequency below 20Hz is infrasound while that above 20,000Hz is the ultrasound.

The sound is a disturbance of molecules which makes it vibrate and sets up a resonance which impacts the next molecule and so a chain reaction until our ears pick it up. Since materials have all their molecules tightly packed together, the disturbance of the adjacent molecules occurs at a faster rate making sound travel more rapidly in the denser medium.

Therefore, a high-frequency sound causes a higher sound pitch perception. The brain perception is dependent on how fast the eardrum can sense the compression changes per second. Older people experience hearing deterioration, the fact that some mischievous young people capitalise on when they develop a special ringtone known as "mosquito" ringtone. The ringtone is usually above the range their much older teacher could hear, so they can communicate in class without the teacher being the wiser. People aged 30 and above stand the chance of being unable to hear above 16,000Hz. You can click here to see if you can hear the ultrasonic "mosquito" ringtone. The sound is higher than an actual mosquito noise at 17.4khz as the real mosquito noise stands between 400 to 600 Hz.

The 2002 French psychological horror drama film, Irréversible made great use of infrasounds to create that scary effects. Check out this 19Hz infrasound; you may need an earphone plus crank up the volume to the max and let me know how you feel.

The infrasound has a bizarre way of affecting the listeners; this was brought to light by Vic Tandy, a British lecturer and researcher on information technology.

He thought his lab was haunted and he later discovered the cause of his trepidation was from a low running newly installed extractor fan.

The natural cause of infrasound includes earthquakes, meteors, ocean waves, etc. and artificial include nuclear explosions, fans, wind turbines etc.

Infrasound is low frequency and thus capable of travelling great distances.

Due to this inherent capability, scientists use infrasound to track herds migrations over vast distances, check for volcanic eruptions and monitor nuclear explosions.

Comprehensive-Test-Ban Treaty Organization (CTBTO) is an organisation in charge of detecting any nuclear bomb testing from any country in the world.

A cleverly hidden underground test may not give off a telltale whiff or residue in the atmosphere, but the seismic and infrasound rumble is one that cannot be masked.

The technology allows for detection of meteors as was evident in the meteorite that hit Russia in 2013. The network of CTBTO's station all recorded the low-frequency infrasound. Astonishingly, the furthest station located at 15,000km in Antarctica was also able to record the sub-audible sound.

Certain animals can produce infrasound such as whales and elephants. The elephants are capable of communicating with herds separated by hundreds of kilometres.

This unique trait of able to hear infrasound gives most animals the ability to run out of a zone just before an earthquake or Tsunami.

The infrasound that a wind turbine creates is now a subject of research and study.

This is as a result of people who are sensitive to sensory stimuli which can cause some form of hypersensitivity and exhibition of symptoms such as a headache, dizziness, difficulty in concentration, unsteadiness, etc.

Conclusion

The low frequency has a lot of uses as well as its annoying sides. The ghostly angle of haunted houses and the connection to infrasound is something I find quite fascinating.

Even though most cannot hear it, it has its effects and uses.

Thank you.

REFERENCES

• ^{Organ music 'instils religious feelings'}
• ^{Some of the scariest sounds in horror movies are the ones you can’t hear}
• ^{The Science of Silence: Disquieting Uses of Infrasound in Movies}
• ^{Ultrasonic Ringtones}
• ^{Two Acoustic Scientists Explain Infrasound}
• ^{Some of the scariest sounds in horror movies are the ones you can’t hear}
• ^{How International Monitors Spot Nukes and Other Rumblings}

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