Jackhammers, jet engines, nuclear weapons.
Are they the best, most loudest sounds of all time?
What is the loudest sound possible?
To find out the limit, all aboard the BOAT.
[BOAT]
Sound is a series of pressure waves.
When it travels through a material like air,
there are periods of compression and rarifaction,
where the molecules are pushed closer together
or pulled further apart.
The distance between each of these periods is the frequency,
and it determines the pitch, whether the sound is high or low.
What humans call "sound" goes from about 20 cycles a second
to 20,000 cycles a second.
This sine wave is currently going through the entire range.
But enough about pitch— let's talk about power.
The amplitude of a sound wave determines how loud we perceive it to be.
Zero decibels is the beginning of human hearing.
It's about the sound of a mosquito ten feet away.
Thirty decibels is a quiet whisper, and a telephone's dial tone
is at about 80 decibels.
If you stand three feet away from a power mower,
you'll hear about 107, and a rock concert can clock over 115.
At 125 decibels, physical pain occurs,
and 100 feet from a jet engine, you'll hear 140.
Now, at 180 decibels, hearing tissue dies instantly.
But what's the limit?
Well, it turns out that a sound wave can only be so loud
based on the material it's traveling in.
A sound wave can cause a lot of compression,
but it can only cause a rarifaction equal in magnitude
to the pressure of the rest of the material around it, like air.
And so at sea level on Earth, that's about 14 pounds per square inch,
which equates to about 191 decibels.
Of course, in different material, the limit is different.
For instance, underwater, sounds can get really loud.
The pistol shrimp creates a sound of 218 decibels
to stun its prey.
It does this by snapping a claw that shoots water so quickly
it forms a cavitation bubble— an empty zone
full of a little bit of water vapor that is crushed
by the entire weight of the ocean.
With that much pressure collapsing it, a cavitation bubble can be crunched
and cause a momentary, fraction of a second temperature
greater than the surface of the sun.
Of course, it is so short lived and such a small event,
it's a relatively low-energy event and wouldn't really hurt humans.
So let's move on to larger events— things that cause pressure so intense,
we can't really even call them sound anymore, but shock waves,
and measure them in Richter.
Now, the Richter scale is logarithmic, which means that each incremental change up is huge.
A large hand grenade produces a shock wave at about 0.2 Richter,
but, Tsar Bomba, the largest atomic weapon ever detonated by mankind,
released the same amount of energy as a magnitude 8.12 earthquake,
and the earthquake recently in Japan registered at 9 on the Richter scale.
An event at 10 or above has never been witnessed by humankind,
but it's estimated that the meteorite smacking into Earth
at the Yucatan Peninsula that wiped out the dinosaurs,
would have been so loud, it would have registered 12.25
on the Richter Scale.
At the very extreme, we have star quakes.
These events occur on dead stars that have collapsed
into neutron stars— so dense that one little teaspoon
of their material would weigh as much as 900 Great Pyramids of Giza.
These structures go through earthquakes just like Earth,
but there's so much energy involved that when it occurs,
it's phenomenal.
The largest ever recorded was in 2004,
when Magnetaur SGR 1806-20 adjusted itself
with a force equal to 22.7 on the Richter Scale.
It happened 50,000 light years away from Earth,
but if it had happened closer, like, say, 10 light years away,
which is still 60 trillion miles, it still would have caused
enough force to have caused mass extinction on Earth.
So there you go—loud stuff.
If you still want more, click on any of these
to hear some really cool audio illusions.
Subscribe to Vsauce 2 for more information,
and as always, thanks for watching.
[Vsauce 2]