Buzz
In the worst-case scenario, your sister's trumpet performance might only make you feel like your head is on the verge of bursting. To actually cause an explosion, you'd need exposure to a much larger instrument for a significantly longer duration.
fontina/Moment/Getty ImagesMain Points
- Sound waves have the potential to harm the human body by accumulating pressure, with the impact depending on frequency and decibel levels.
- Prolonged exposure to extremely high decibels (above 177 dB) at certain frequencies can lead to physical injuries, such as irregular breathing and joint damage, though achieving the lethal threshold of 240 dB is virtually unattainable.
- Nonlethal sound-based weapons, such as the Long Range Acoustic Device (LRAD), highlight the powerful yet constrained potential of sound as a weapon.
In "The Calculus Affair," a volume from Hergé's iconic Tintin comic series, Professor Calculus creates a sonic device so powerful that a hostile government kidnaps him, aiming to force him into developing acoustic weapons. The sinister military leaders plan to annihilate entire cities using powerful sound waves. Fortunately, Tintin, the intrepid reporter, and his loyal companion Captain Haddock save the professor and thwart the evil scheme just in time.
But does this storyline have any scientific basis? Can sound truly be lethal? If yes, how does it work? Sound is created by waves of pressure traveling through a medium, such as air. These waves can also pass through solids and liquids, meaning they can traverse the human body as well. In theory, sufficient pressure buildup can cause harm.
When discussing sound, the two critical measurements are decibels (dB) and hertz (Hz). Decibels measure sound intensity, while hertz indicates the frequency of sound waves. A typical conversation ranges between 50 and 65 dB. A lawnmower operates at about 85 to 90 dB, a jackhammer increases the noise to 110 dB, and a nearby jet engine can reach up to 140 dB [source: NIH].
Humans can only perceive sound waves between 20 and 20,000 Hz, but frequencies outside this range can still impact us. For example, sitting in front of a subwoofer emitting 19 Hz at 100 dB won’t produce audible sound, but you’ll feel the vibrations. At 19 Hz, your eyes may even distort, as this matches the resonant frequency of the human eyeball. Exposure to 177 dB sound waves at 0.5 to 8 Hz can disrupt lung function, causing irregular breathing and shaking your bones. Short-term exposure may harm joints, while chronic exposure can lead to nausea and vision problems [source: Horowitz].
The European Space Agency (ESA) states that being accidentally trapped in their Large European Acoustic Facility (LEAF), designed to test satellite resilience, would be fatal due to the intense sound levels. A crucial factor is the enclosed environment, as sound waves disperse too quickly outdoors to reach deadly levels. Despite this, researchers have explored sound as a potential weapon. For instance, calculations show that 240 dB would be needed to cause a human head to explode—a level of noise nearly impossible to generate. Even at its peak, the ESA’s LEAF only reaches about 154 dB [source: ESA].
For non-lethal applications, sound-based weapons can be highly effective. Imagine deterring a group of Somalian pirates from approaching your cruise ship. A long-range acoustic device (LRAD) emitting 150 dB of intense noise can cause permanent hearing loss even at 1,000 feet (300 meters), making it a powerful deterrent [source: Blenford].
