Name: ノイズとは何か？(音・周波数・ピッチの科学と数学) (What is up with Noises? (The Science and Mathematics of Sound, Frequency, and Pitch))
Uploaded: 2021-01-14T10:30:27.000Z
Duration: 12 min 49 s
Description: VoiceTubeの動画で発音を聞きながら英語表現を覚えよう！学べる英語：

When things move, they tend to hit other things.

When I pluck this string, it's shoving back and forth

and they push against other air molecules

that they're not literally hitting so much as getting

too close for comfort until they get to the air

And then that sends signals to our brain to say,

This string is pretty special, because it

likes to vibrate in a certain way and at a certain speed.

When you're putting your little sister on a swing,

It takes her a certain amount of time to complete a swing

If you time your pushes to be the same length of time,

then even general pushes make your swing higher and higher.

you'll just end up pushing her when she's swinging backwards

and instead of going higher, you'll dampen the vibration.

It wants to swing at a certain speed, frequency.

the sound waves I'm singing will push against the string

at the right speed to amplify the vibrations so that that

string vibrates while the other strings don't.

Firstly, we've got this ear drum that gets pushed around

And then that pushes against some ear bones

that push against the cochlea, which has fluid in it.

And now it's sending waves of fluid instead of waves of air.

But what follows is the same concept as the swing thing.

which has a membrane called the basilar membrane.

Now, when we have a viola string, the tighter and stiffer

it is, the higher the pitch, which means a faster frequency.

The basilar membrane is stiffer at the beginning of the tunnel

vibrates at high frequencies at the beginning of the cochlea

and goes through the whole spectrum down to low notes

So when this fluid starts getting pushed around

at a certain frequency, such as middle C,

there's a certain part of the ear that vibrates in sympathy.

going to push against another kind of fluid

And this fluid has hairs in it which get pushed around

by the fluid, and then they're like, Hey, I'm middle C

and I'm getting pushed around quite a bit!

Also in humans, at least, it's not a straight tube.

You can make the note C on any instrument.

But that C sounds very different depending

on whether I sing it or play it on viola.

It's not exactly true that pushing with the same frequency

that the swing is swinging is the only way

You could push on just every other swing.

And though the swing wouldn't go quite as high

as if you pushed every time, it would still swing pretty well.

In fact, instead of pushing every time or half the time,

you could push once every three swings or four, and so on.

There's a whole series of timings that work,

though the height of the swing, the amplitude, gets smaller.

So in the cochlea, when one frequency goes in,

shouldn't it be that part of it vibrates a lot,

but there's another part that likes to vibrate twice as fast,

likes to vibrate three times as fast and four times.

And this whole series is all sending signals to the brain

that we somehow perceive it as a single note?

Let's also say we played the frequency that's

twice as fast as this one at the same time.

It would vibrate places that the first note already

our brains perceive these two different frequencies as being

almost the same, even though they're very far away.

Keep that in mind while we go back to Pythagoras.

You probably know him from the whole Pythagorean theorem

thing, but he's also famous for doing this.

He took a string that played some note, let's

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ノイズとは何か？(音・周波数・ピッチの科学と数学) (What is up with Noises? (The Science and Mathematics of Sound, Frequency, and Pitch))

perceive

pattern

separate

subconsciously