(ORDO NEWS) — In 1883, the Indonesian volcano Krakatau (still active) erupted, literally destroying the island, tossing giant stone fragments to a height of more than 27 kilometers.
The noise from this event was so loud that the sailors, located 65 kilometers from the volcano, received fatal damage to the eardrums, which led to complete hearing loss. Even at a distance of more than 160 kilometers, the volume was 170 decibels (dB) – enough for partial hearing loss.
It’s hard to believe, but the sound of the eruption could be heard 4800 kilometers from the epicenter – it’s like being on the East Coast of the United States, hearing the sound made in London.
The sound generated by Krakatoa was originally so loud that it went beyond what we commonly refer to as “sound”.
What is a decibel (dB)?
The decibel is named after American and Canadian scientist Alexander Graham Bell, but one “bel” is too big, so scientists divide it by 10, which gives us “decibel”.
- Own breathing – 10 dB
- Whisper – 20 dB
- Normal dialogue – 60 dB
- Noisy cafe – 70 dB
- Electric drill – 95 dB
- Jill Drake from the UK, who in 2000 got into the Guinness Book of Records for the ability to scream the loudest – 129 dB.
What is noise?
Absolutely all noises arise as a result of the collision of air molecules with each other along a chain stretching from the sound source to the eardrum (sound receiver).
For example, when you hit your fingers on a table, the surrounding air molecules are repelled and begin to fly apart.
On their way, molecules meet neighboring molecules, collide with them and transmit sound (vibrations) to them, which neighboring molecules transmit to their neighbors, and so on, until the sound reaches the eardrum, which sends a message to the brain for interpretation into understandable information.
Each molecule travels only a tiny distance, but a wave has time to form, which travels from the source of the sound to the ear. A sound wave consists of areas of high pressure with more molecules followed by fewer areas of low pressure.
Is there a volume limit?
Once you reach 194dB (the fundamental limit of loudness in air), there will come a point when the low pressure areas are completely empty – all air molecules move into the high pressure areas.
This will cause the air molecules to no longer move smoothly back and forth, and the sound wave will turn into a shock wave.
The shock wave from Krakatoa was so powerful that it circled the Earth four times !
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