Sound is a form of energy that travels through a medium as waves of pressure. While many sounds are part of our everyday experience, some natural phenomena can generate acoustic energy on a scale that defies easy comprehension, leading to incredibly powerful and far-reaching sound events.
The Loudest Sound Ever Recorded
The most powerful sound ever recorded originated from the eruption of the Krakatoa volcano on August 27, 1883. Located between the islands of Java and Sumatra in Indonesia, this volcanic explosion released immense energy, estimated to be equivalent to a 200-megaton bomb. The sound produced at the source has been calculated to be around 310 decibels (dB).
This blast was powerful enough to rupture the eardrums of sailors on ships approximately 40 miles (64 kilometers) away from the volcano. The eruption also obliterated more than two-thirds of the island, launching an ash plume an estimated 17 miles (27 kilometers) into the atmosphere.
Understanding Extreme Loudness
Sound intensity is typically measured in decibels (dB), a unit that operates on a logarithmic scale. This means that each increase of 10 dB represents a tenfold increase in sound intensity, and a perceived doubling in loudness. For instance, a sound at 20 dB is ten times more intense than a sound at 10 dB, and a sound at 30 dB is a hundred times more intense than 10 dB. This logarithmic nature helps to manage the vast range of sound pressures our ears can detect, from the quietest whisper to the loudest roar.
The human threshold of pain from sound typically falls between 120 and 140 dB, where exposure can cause physical discomfort or immediate damage to hearing. To put Krakatoa’s magnitude into perspective, a nearby jet engine might produce around 140 to 150 dB, while a loud rock concert could reach 110 to 120 dB. At approximately 194 dB, the fluctuations in air pressure become so extreme that the acoustic wave transitions into a physical shockwave, which is what occurred near the Krakatoa blast.
The Far-Reaching Impact of the Sound
The sound from the Krakatoa eruption extended far beyond its immediate vicinity, traveling across vast distances and leaving a global imprint. The immense blast was heard as far as 3,000 miles (4,800 kilometers) away in locations such as Rodrigues Island near Mauritius and Perth in Western Australia. In these distant places, the sound was often described by witnesses as resembling distant cannon fire, taking roughly four hours to reach them due to the speed of sound.
The atmospheric pressure wave generated by the eruption was so powerful that it circled the entire globe multiple times. Barographs, instruments used to measure atmospheric pressure, registered these pressure spikes for several days following the eruption. Reports indicated that the pressure wave from Krakatoa reverberated around the Earth three to four times, causing noticeable spikes in pressure that were recorded by weather stations worldwide for up to five days. This propagation demonstrated the extraordinary scale of the event, affecting the planet’s atmosphere on a truly global scale.