[Honking car horn, clock ticking, radio signal]
You hear that?
That's the sound of silence.
Well, not really.
Absolute silence doesn't really exist in our world, but there's an entire field of
study devoted to the science of silence.
Why?
Well, it plays a huge part in our
daily well-being.
Our brains are hard-wired to perceive sounds even when
they're not there.
Moviegoers have felt this for generations but, thanks to
modern technologies, scientists know this to be fact.
A recent study by the
University of Southern California demonstrated how silent films could
elicit content-specific reactions in your brain's auditory cortices.
In other words,
as you watch these images your brain is pulling from memories and past
experiences to fill in the blanks.
This effect is sometimes referred to as
"hearing in your mind's ear" and it's the reason why, when your favorite song cuts
short on the radio,
You can still hear it.
So if we can never really experience
silence in nature, can we create it artificially?
At facilities like 3M's campus in St. Paul, Minnesota,
silence becomes science.
We're in the anechoic chamber here in the 3M Center.
And this is a room that
was built back in '64 and eats echoes.
Sound just hits the wall and dies.
Anechoic or non-echoing chambers such as these are used by scientists to study how
sound operates in a truly quiet environment.
When you're doing science
you can control temperature, you can control pressure, flow, and you never
thought you could control sound.
But in this room we can do that.
Why do scientists
care about capturing quiet?
When something's quiet you think it's high quality,
you go into a hotel room and the air conditioner, that makes a lot of
noise. What does that tell you? It's cheap.
Quietness is a sign of quality.
So, how does it all work?
The secret of silence is the chamber's design.
It's a building within a building.
Every surface is covered in an
intricately arranged series of fiberglass wedges.
As sound waves
propagate out from a source, they get trapped between these wedges, bouncing
back and forth until they dissipate.
Even the floor and ceiling are covered,
creating a completely spherical surround-sound setup of silent seclusion.
What does it sound like?
Well, while a balloon popped in a reverberant room might sound
like this:
Inside 3M's anechoic chamber, it sounds like this:
It's gone.
So, how do the physics of this chamber relate to our daily lives?
By understanding how sound waves work 3M researchers have been able to develop
technologies that absorb and reduce noise in virtually every environment
that surrounds us.
Airplanes for instance, use a specially designed foil tape to
dissipate vibration and noise in the cabin.
Even if it can't stop that crying baby.
Modern cars meanwhile, keep noise to a low hum by using microfiber technology.
Without it, conversation in cars would be a screaming match. And once driverless
cars are widespread, there will be a lot more time for talking and work on the road.
These quality of life improvements can also have a direct impact on your
mental health.
A growing body of research has shown how chronic levels of noise
can lead to sleep loss, heart disease, and high blood pressure.
On the flip side,
quiet environment seem to have directly positive benefits. Noise
pollution is harmful to the human.
It wears you down, it makes you anxious, it
makes you tired.
There's only so much noise you can take and then your brain
needs to relax.
These things always work, even when you're asleep.
Removing excess
noise not only lowers our stress levels, but even promotes the development of new
brain cells.
Among mice, at least.
You can reduce noise and have a much more
pleasant life.
You know, you can have nice conversations over the dinner table when a
jet's flying over, if you can control the unwanted noise.
Wherever you are, there's
going to be noise.
We live in a noisy world.