You walk into an old house and the door hinges creak eerily. Slowly you step across the living room as the floorboards groan. The sound of an empty chair rocking back and forth is drowned out by slow, deep footsteps. There’s a loud knocking on the ceiling, and a loud dragging sound above your head fills the room. KABOOOOM! Thunder rattles the rain-drenched windows and then suddenly everything goes deathly quiet.
Tick tock, tick tock, tick tock, tick tock. An ominous loud ticking reverberates throughout the house, but there’s no clock in sight.
Either you’ve just walked onto the set of a horror movie, you’ve met Linus’ Great Pumpkin or your architectural structure needs some acoustical touch ups.
ACOUSTICS 101 SERIES: Part 1 / Part 2 / Part 3 / Part 4 / Part 5 / Part 6 / Part 7
In the entertainment industry, all sound falls into three categories: music, dialogue and effects. In a horror film or haunted house, all these types of sounds are considered effects and are performed and recorded on a Foley stage or pulled from a sound library. A Foley stage is essentially a recording studio filled with every object possible that can create the noise of a sound effect. Foley artists walk on glass, shake bottles, crunch potato chips and physically create each sound in a film one by one.
In the real world, every sound in a structure can be traced back to its acoustical roots. Creaky door hinges are rusty, too tight or in need of a good oiling. Floorboards squeaking or groaning are either incorrectly fastened or not plumb or true. Scary loud footsteps fall under Impact Insulation Class, which is designed to measure footfall noise between different floors of a building. Loud rattling of windows in a thunderstorm are due to glazing not being set correctly in windows, older style windows or by not using double-paned argon-filled window assemblies.
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As for ominous loud ticking clocks, either you’ve been watching too many scary movies or you have very thin walls with no acoustical insulation and thin drywall layers. This too can be easily solved with a variety of wall types from traditional staggered stud to new high-performance ultra-thin ZR wall types only 3.75” thick rated at 70 STC.
Unintended Negative Effects of Noises
Besides the obvious horror film-style noises which exist in reality all too often, there are scary noises in the real world that have an acoustically disturbing and dramatic effect on the lives of humans.
The promise of free wind energy turns out to have some spooky side effects. The larger the blades, the more efficient wind turbines can create or transduce energy from wind to electricity. However, the larger the blades, the lower frequency noise they make. Studies show that turbines create low frequency noise similar to earthquakes but at lower amplitudes/volumes. The result is like a bad dream or nightmare. Turbines are making sounds as low as 1 hertz. Yes, one hertz, the lowest frequency possible before sound turns into DC.
From 1-30 hertz and as high as 200 hertz, turbines create a low rumble, causing long term sleeping disorders by disrupting REM sleep on a chronic basis. Imagine having the same nightmare every night for years until you realize your neighbors have the mother of all subwoofers attached to their nightlight.
The impact of subway noise on surrounding neighborhoods shows that increased cardiovascular disease is related to sleep disorders caused by rail noise in urban areas. While most spooky sounds are low frequency noise, subways do create a wider variety of noises than wind turbines or deep footsteps, thereby having a wider and deeper range of effects. These are similar to having a spooky bad dream including, but not limited to:
- Increased heart rate
- Lack of deep REM sleep
- Increased blood pressure
- Elevated anxiety and stress levels
Last, but not least, is our favorite means of long-distance travel, airplanes. Because of new engine designs, noise from aircraft is getting better with each generation. Nevertheless, there is still a significant impact on local environments and the people living there. Similar to subway noise, physiological issues include:
- Cardiovascular issues
- Cognitive issues in children
- Elevated anxiety
- Decreased attention spans due to sleep deprivation.
Studies in Europe show a clear correlation between learning disabilities and aircraft noise.
How to Balance Noise
There’s a certain amount of common sense to acoustics. Anyone who has ever had a bad night’s sleep and was unable to think clearly the next day due to a loud neighbor, subway or plane knows intuitively it’s bad for your brain. Billions of dollars in research later, we have the scientific data to prove what each and every person knows: loud sound over prolonged periods of time, (or even overnight) is unhealthy for people.
All in all, the moral of the story is to enjoy All Hallows’ Eve, scare yourselves until you jump out of your skin and have a good fright! Then get a good night’s sleep in a dark, quiet, peaceful room and do some yoga or meditate for an hour.
The good news is that there are many ways to rejuvenate yourself. Deep sleep, meditation and exercise are all excellent ways to counterbalance the negative effects of exposure to loud noises and acoustical stress.
Remember, acoustics is incredibly fun. As the science behind all sound, it brings us music, language and a wide world of intriguing sounds. It can teach us to care for our health and improve our quality of life in many new ways.