(dramatic music)
(wind whistling, leaves rustling)
(crows cawing)
(door creaking)
- Hey. (sighing)
I'm Jake and before being trapped in a world
with sound-sensitive murder beasts,
I had two loves in my life: science and movies.
So I decided to put myself in one of my favourite monster films, A Quiet Place,
to find out... Hey, hey!
Could you be quiet back there?
You don't want to die like the kid in the movie did, huh?
Horribly. Horrible death.
(chuckling) Kids! Am I right?
Bundle of laughs. But this one is pretty loud.
But I found him wandering around, decided maybe I'd help him find his family
while I look for my... missing Vsauce family.
And as long as we don't make a lot of sound,
I think we should be okay.
Which got me thinking... hey, kid! Come on!
What is sound?
What exactly does it mean to hear?
Is it possible
to weaponize sound? (loud whirring)
Perhaps most importantly,
could you stay quiet enough to survive the wrath
of a bloodthirsty alien with superhuman hearing?
(clicking)
(female voice): The alien says...
(growling)
- Could you survive A Quiet Place?
That was close.
The kid? Oh, he should be fine.
Also, this is a rather serious way to illustrate
that we can't make a sound.
And speaking of which,
sound is really a series of longitudinal pressure waves
that travel through a medium, like air or water.
But they can also travel through solid objects, too.
Hearing is just the detection of these increases
and decreases in pressure, that occur at regular intervals
as small segments of air are compressed.
These rapid changes in pressure enter our ear canals,
and vibrate our eardrums.
Those vibrations are translated into electrical pulses
in the middle and inner ear,
which then travel to the auditory cortex
where the brain processes them.
And we perceive sound.
The mechanical energy of sound turns into an electrical energy.
Which is also how microphones and speakers work.
And speaking of microphones, this little device contains one
and it uses it to measure the intensity of sound signals.
Could be pretty useful in figuring out whether we're being loud enough to get eaten by
one of those horrific monsters that's making my life hell.
Oh, you're still alive!
Ah, kid, I really thought I lost you out there.
It's good to see you even... wait, what is that?
Don't you... Don't you do it!
(computerized beeps)
(growling in the distance, dramatic music)
Oh, no!
Kid! Come on!
We need to find a quiet place!
But what is... the quietest place?
What is... quiet?
Can we imagine it in our minds?
It's kind of a difficult concept to understand,
'cause have you really experienced true quiet?
Because sound, as we know, travels.
It hits surfaces, bounces back off, it reflects.
So if we wanted to, we'd have to create a room
filled with sound panels like the ones behind me
that absorb those reflections.
If we wanted to find the quietest place,
we would need an anechoic chamber.
The world's quietest place is an anechoic chamber
that had a decibel level of negative 20.6.
To put that into perspective,
zero decibels is the lowest a human ear can hear.
These rooms work by absorbing all reflected sound,
leaving you with only direct sound.
So if there's nothing in the room to make noise,
then there is no noise. Right?
Now, the only way to experience an anechoic chamber
is to actually be in an anechoic chamber.
And when you're in there, you would notice, even though it's quiet,
there is still sounds.
So I'm gonna do my best right now to demonstrate that for you,
so... you know what? Let's get rid of the air conditioning noise?
(clicking) Alright, that's better.
And also, the hum of the lights. (clicking)
You know what? Let's just get rid of all ambient noise around me.
And now, it's just my voice, but even the microphone that's picking up my voice
is making noise... it's picking up other sounds.
So... let's isolate my voice.
Okay now, it's just you and me. But we can still hear sound
coming from right here,
so let's get rid of that too.
(soft thumping)
When we remove all external noise,
what we're left with... (heartbeats)
(gulps) ...is internal noise.
(breathing)
That is the sounds of our body.
The blood pumping through your veins.
Your eyes blinking.
The fabric on your clothes when you move.
We are always surrounded by sound.
So here on Earth, there is no true quiet.
That is, a place completely devoid of sound.
Because as we remove the noises around us,
we start to hear things that we generally don't,
and if we can hear those sounds, then the aliens can probably hear them too,
which makes sense 'cause in the movie,
they would mask their conversations by going to a loud, consistent waterfall.
That would be pretty useful right now.
That was a pretty cool demonstration, right? Right, kid?
Kid?
(sighs)
Well, he's probably just... a lot faster than me.
(twig cracking)
We should... keep moving, though.
(soft music)
Oh! Hey...
Uh, sorry to bother you, I'm just looking for a little kid. He's been walking around--
- Yeah, yeah, sorry. Okay. That's my bad.
So I'm looking for a little kid and he's pretty loud...
and the aliens, you know, they're pretty diabolical, so I've just been...
- No! I don't think they followed me at all.
Hey, uh... what are you doing?
- So... you've been able to keep yourself safe here from the monsters.
But what's your secret?
- Okay, so... I don't really know how to ask this... um...
- Yeah.
- We can actually have you experience this at home.
We've isolated some frequencies of everyday sounds
to see if you can guess what they are
just from feeling the speakers
on whatever device you're watching with.
So... put in some earplugs or some unplugged headphones
and put your hand on your device's speaker.
We'll play four sounds, guess what they are and then we'll visually reveal each one.
(barking)
(engine roaring)
(honking)
(jackhammer drilling)
So, could you feel through your fingertips
the vibrations from the sounds that we played?
And could you tell what they were?
Okay, so now that we've experienced sound by feeling it,
can we experience sound by seeing?
Good question! I'll be right back, Rikki.
Here, we have a speaker that I'm gonna cover in different substances
to help show the physical vibrations generated by sound.
This one we've covered with sand,
while this one is covered in a substance made by both cornstarch and water.
It's a non-Newtonian fluid, meaning it is both a liquid and a solid,
depending on the amount of force exerted on it.
Okay, let's drop the bass.
(classical music)
The sand is sitting atop a Chladni plate,
a piece of metal that restricts sound waves to a finite space,
allowing us to see the standing wave pattern associated with different frequencies.
Now each frequency causes the plate to vibrate in a different way.
And the sand arranges itself along the lines of those vibrations.
Where there are the least vibrations, that's called the nodes of the standing wave.
And they move away from the parts with the most vibrations,
the anti-nodes.
So you are actually seeing the sound as it moves across the Chladni plate
and through the sand.
The non-Newtonian fluid, our oobleck,
provides more of a three-dimensional visualisation of the standing wave pattern.
The peaks and valleys of the oobleck are the antinodes.
And the flat areas are the nodes.
Fun fact: standing waves that move through liquid
are called Faraday waves.
So both the sand and the oobleck
make the normally invisible, that is, sound waves,
visible.
Plus, it just looks really cool.
(end of the classical music)
You know, you can come with me if you want.
You'd be a great help.
- Thank you and I will. Safety first, right?
(screams)
(muffled high-pitched ringing)
No, you save yourself, Rikki, I got this.
Come on!
(dramatic music)
(growling)
Huh... (indistinct)
And as always... thanks for watch...!
(crashing)
(muffled soundscape)
- Jake?
Hey, Jake?
- 12 Tone? - Hey, man!
It's nice to see the trap door works. (Jake grunts)
- Yeah, I'm totally fine as well.
Hey, 12-Tone!
- Oh, sorry! I was working on a really tricky modulation.
Hey, you wouldn't happen to know a good pivot chord
from E to B flat, would you?
- No, I've... been a little busy
trying to survive, and also,
looking for my Vsauce family. Have you seen these dudes
and oh, maybe a little kid? He's like yea high, likes to make noise.
- No, dude! I've been down here.
Don't you know there's aliens running around up there?
They've got superhuman hearing.
- Yeah. I know.
- Ah, but did you know we might be able to defeat it
by weaponizing sound?
So these aliens have an extreme sensitivity to sound.
That might seem like a superpower,
but couldn't it also be a weakness?
I have a theory that we can use sound itself to fight them.
After all, what would your weapon of choice be
if you had to fight someone with an extreme gluten sensitivity?
Gluten!
- I gotta admit, that logic is sound.
So a young person can usually hear sonic frequencies
between about 20 hertz and 20 000 hertz.
And just as a refresher, hertz is a unit of cycles per second.
So a 20-hertz sound is created when air alternates
between low and air pressure 20 times in a second.
And as adults age, the high-end of their hearing deteriorates.
So if I play this 18 kilohertz signal...
(high-pitched ringing)
...it acts as a kind of dog whistle for younger listeners
who still have the high-end of their hearing intact.
It's the same principle as an actual dog whistle,
which works because dogs can hear up to 45 kilohertz,
which is well above the human range.
So what was that about making a weapon out of sound to defeat the aliens?
- Well, people have come up with a lot of interesting ways of weaponizing sound.
You've probably heard of that thing where an opera singer
shatters a wine glass with just the power of their voice.
(high-pitched voice)
- Breaking a glass with sound is very cool,
but probably not powerful enough for our needs
because in the film, A Quiet Place,
they use a high-frequency sound weapon to kill the aliens.
So, is there a device in real life that can do the same thing?
Well, we just happen to have a machine to test just that.
And what are we testing it on? Me.
Our sound cannon is made up of four speakers
with their cones positioned to send sound waves in the same direction.
To discover the power and efficacy of this sound cannon,
we're testing two factors.
Distance from the weapon
and the frequency of the sound being emitted.
It's connected to a frequency generator that will provide the sound, which will be shot at me.
Alright... let's make some noise.
I am five meters away from the device,
now let's take it up to 4,000 hertz, please?
(trilling sound)
This sound generated is incredibly annoying.
And we don't want to subject you to it,
so please enjoy Bach's Cello Suite number 1.
(Bach's Cello Suite)
We've set the device to about 130 decibels,
the same volume as a jet engine taking off.
While the volume will cause some pain in my ears,
it won't incapacitate me.
(trilling sound)
Alright, now, let's just go up to two meters.
(trilling sound)
At two meters, the effects are immediate.
The pain is overwhelming, freezing me in place.
Turns out the pain is because the frequency is triggering
my auditory nociception system.
A single set of neurons in your ear that react to high frequencies.
When cells in the area are damaged,
like by a really high frequency,
they release a chemical that activates the auditory nociception system,
which in turn signals the brain that you are in extreme pain.
Although this really hurts my head,
unlike in the movie, it probably won't make it explode.
Nuts.
I felt like there was this viscous liquid in my ears
and I couldn't really hear; I still can't really hear!
Uh... I don't know what level of volume I'm at,
but don't do that, it's a very good deterrent,
however, it would not kill the alien.
If only we had some sort of hand-held
narrative-friendly sound cannon.
- Like this?
- 12 Tone! That is perfect!
- It's actually pretty simple. As you can see,
I hooked up a cassette tape to a megaphone,
ran it through a frequency oscillator
to pump up the signal and that's pretty much it.
- You know, this is amazing, do you think I could borrow it
'cause it could be very helpful in trying to find my Vsauce family
and maybe even that kid if I see him again.
- Yeah, for sure. - Thanks.
- Or... do you need some backup?
I could come with you, help you look.
- Yeah, that would be great. And... you get some fresh air,
you know, that might be good for you.
- Yeah, plus, you know what they say,
two heads are better than one. So if we work together,
I'm sure we can find your friends.
- That is true.
- It just goes to show the power of a good collaboration.
I mean, you take some scientific rigor, add in some musical curiosity
and boom, you've got a sound cannon!
- Volume down... - I'm just saying:
how cool is it that you and I were able
to make a weapon that could destroy these aliens?
(growling)
- Oh, no!
(growling)
(alien trilling)
(hissing)
(electronic beeping)
Oh, kid! You're still alive somehow!
Hey! Listen to this!
(high-pitched sound)
Why?
Oh, kid! Glad you decided to make some more noise.
Wait. No. No!
(electronic beeping)
(footsteps approaching)
(aliens trilling in the distance)
And as always, thanks for watching.
(growling)
This season on CYSTM...
- Ah!
- Oh, no!
Come get some!
Let's make me hypothermic. Tear this body apart.
Oh! (both): The need for speed!
- I don't think they're gonna survive this one.