If you've ever had to cover your ears at the sound of a jackhammer or a passing motorbike,

you'll know how it feels for something to be too loud.

But compared to the loudest sounds it's possible to hear, these things are barely a whisper.

Some sounds produced by nature, animals, and human machinery alike get so loud,

merely standing in their vicinity would be enough to kill you.

On Sunday, August 26, 1883, one of the loudest sounds ever recorded shook planet Earth. The eruption of

the Krakatoa volcano. Even a whopping 100 miles away from the source, the sound of the eruption was

registered at 172 decibels. Now, we all know volcanic eruptions can get pretty loud. But let's put that into perspective.

If an explosion of that caliber occurred in downtown Los Angeles, San Diego residents 100 miles away,

would hear a sound louder than standing right next to a space shuttle launch.

The shockwaves of Krakatoa's blast circled the planet in every

direction four times over, rupturing the eardrums of sailors some 40 miles away from the eruption.

Pretty crazy, right? But how can sound be so dangerous? Well, to understand what makes certain sounds

so loud, and why those sounds can hurt a lot,

it helps to understand how sound actually works.

When an object vibrates after being struck, blocked, or energized in some other way,

it produces sound waves.

Unlike the up-and-down transverse waves of the ocean,

sound waves are longitudinal and look more like a moving spring. This is because

as sound waves travel along, they compress and expand the medium they're moving through, creating

differences in pressure. Some things like the tightly stretched membrane of your eardrums

can translate these changes in pressure into signals, which we perceive as sound once our brain

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