Loud noises can be extremely annoying. And if you happen to have a noisy neighbor who regularly plays hardcore metal rock at a very high level or live near a police siren testing facility, you know how it feels. We already know that sound can definitely hurt you, but is it possible for a sound to be so powerful that it can kill you?
Yes it can, explains Julian Huguet of DNews in the video “Can Sound Kill You?” And, The European Space Agency has such a powerful sound system in its arsenal that, at “maximum output” no human could survive hearing.
The horn shown below is one of four gigantic horns at the Large European Acoustic Facility (LEAF) in Noordwijk, the Netherlands. These horns use nitrogen gas and can produce a range of noise up to more than 154 decibels. The ESA actually thinks sound as loud as this (154 decibels) could definitely burst your eardrums right away and cause serious damage from long-term exposure. But don’t panic, they aren’t using their “Horn Section of Doom” to kill humans; they are using it to test satellites to see if they can withstand the sound of a rocket launch.
Sound is a mechanical compressional wave cause by oscillations in air pressure. The greater the change in average air pressure, the higher the amplitude. Amplitude actually refers to the change in pressure as the sound waves propagate through different mediums. So, if you increase the amplitude of a sound, you are making it carry more energy and thus you will interpret the sound to be louder. And, if you decrease the amplitude, you will perceive that sound to be softer.
Sound can break things into pieces, if it is loud enough or is at the right frequency. Every object has a natural frequency known as resonant frequency. At this frequency, an object readily vibrates. Let’s take a ‘glass’ for example. If you tap a glass next to your ear, you will hear a sound. That sound is the right frequency for the glass to start to vibrate. Well, if you stimulate the glass with a sound of same frequency, the vibrations in the glass will become more intense; and if the vibrations become more and more intense, the glass will break. So if you are to break glass or shake something into pieces, you just need the right amount of frequency. It does not have to be a very high one.
Do you know why the Space Shuttle’s Launch Platform would dump 350,000 gallons of water onto itself during launch? It is to dampen the sound, which otherwise the 195 decibels the engines pumped out would put too much stress on the wings and eventually damage the Shuttle.
It has been speculated that 195 decibels can actually do enough damage to your organs that you would not survive. Also, it is believed that the threshold for death is usually around 185 to 200 decibels. Because “sound waves with that big of a pressure fluctuation” could cause an air embolism (forcing an air bubble into your blood) in your lungs which would cause cardiac arrest, seizures or lungs to simple burst due the increased air pressure.
There is not a lot of research in this area. But, Jurgen Altmann, Professor of Physics at Technische Universität Dortmund, Germany once showed that a sound wave at 210 decibels caused lung damage. Also, an experiment on whether or not the loud noises caused by piles drivers would cause injuries on fish (with and without air bladders) found that the fish without air bladders showed no injuries on exposure to loud sound, while the other fish with air bladders were severely damaged by sound alone.
154 decibels is considered enough to harm you, and it is just 40 decibels below the lethal threshold. You may ask why it is so difficult, or perhaps impossible to add another 40? Well, as Julian explains, the decibel scale is logarithmic, which means a sound at 90 decibels has 10 times the energy as a sound at 80 decibels. For ESA horns to reach the lethal threshold, the sound wave they generate would need to have 10000 times more energy.
“If you’d want to make someone’s head explode a la Scanners, you’d probably have to have 100 times the amplitude again, going all the way up to 240 decibels,” says Julian. “And keep in mind, you’d have to put the person’s head right next to the sound source for that to happen because sound dissipates.”