“The last sound you’d never hear.”

In the latest video from Joe Hanson’s It’s Okay to be Smart series, Joe takes a look at the science of sound. Specifically, he wants to know what the loudest possible sound is. Hint: it’s between deafness and death.

The “loudness” of a sound is better described as the intensity of the pressure waves our eardrums pick up. Measured in decibels, a logarithmic ratio of two power quantities, the intensity of a sound actually does have a limit. At 194.1 decibels and above, sound waves are distorted and the pressure waves are better described as dangerous shock waves. At a few decibels higher than this eardrums rupture. Less than 10 decibels higher than this limit and the sound can literally kill you.

But what really blew my mind is that we’ve routinely made “sounds” going far beyond this kill zone in our space program. The launch of a Saturn V rocket, for example, produces around 220 decibels, which ignites grass a mile away with the sound alone. The launch pad has to dump 900,000 gallons of water a minute below the rocket for absorption or the reflected sound waves would rip the rocket apart. Now that’s a bang.

—

IMAGE: Saturn V rocket, NASA