Meet Noisy. The robot that… make noises. Most people don’t appreciate his somewhat
strange purpose, and find him irritating at best. But in all actuality, this little robot can
provide a unique excursion into the world of sounds, because his memory contains all
the tones of the universe. Today we’ll find out just what Noisy can
do, and discover a lot of intriguing things along the way. It’s pretty easy to help him, all I need
to do is set my imagination free and give him a challenge! Let’s try this. Noisy, can you give us the quietest sound
imaginable? Hmm, it seems like nothing’s happening here. We’re…..still waiting, Noisy. Oh, I know what the problem is. The loudness, or should I say quietness of
this sound, is nearly immeasurable, because what Noisy is broadcasting right now is the
sound of air molecules moving around us. And they move all the time, vibrating, and
therefore technically making a sound. This is why the superhuman characters in movies
seemingly have so much trouble adapting to their powers, like super hearing: they can
hear the air itself, and anything else would be too much noise to deal with! Good thing we don’t have to worry about
that, so let’s move on and come up with another task for our little robot friend. Noisy, can you make the sound of the quietest
room in the world? The sound here is around -20dB, which means
that it’s 20dB below the hearing threshold of our ears. This room isn’t just quiet; it’s basically
swallowing any sound it encounters. This room is called the Microsoft chamber,
and is found in Redmond, Washington. It holds the Guinness World Record as the
quietest place ever. Wow, it seems like my own voice became a little
muted here. That’s happening because Noisy isn’t just
playing recorded sounds – no memory can contain this much information. Instead, sounds are coded in his memory by
their qualities, like intensity, pitch and even the density of the space they’re spreading
through. Noisy is a one-of-a-kind robot that, using
these qualities, can make the air itself move as if a particular sound was manipulating
it. This gives us the unique opportunity to hear
anything – from the depths of the ocean, to the vacuum of space. For example: Noisy, what would be the quietest
sound that we could actually hear? Sounds familiar. This is the sound of you calmly breathing,
and your heart beating. At just 10 dB, we won’t ever notice it in
our everyday life. But remember that we’re still in the quietest
room in the world, so you can hear it clearly. Fun fact: we aren’t used to hearing our
own heart and lungs. Our mind perceives these sounds as a distress
call, because if your heart beats loudly and your breath is too heavy – this typically
means that you’re in danger. The brain will desperately scramble to figure
out the reason for this reaction; which is why no one, to this day, was able to be in
the anechoic chamber for longer than 55 minutes. It’s really uncomfortable! Let’s move on to something more tangible. To hear 60 dB I don’t even need Noisy. This is about the volume of me talking to
you right now. Or anyone talking to anyone else, actually. A change of 50 dB may seem drastic, but this
level is a real comfort zone for our ears. Turn the volume up another 50 dB, and you’ll
run from the source of the noise as fast as you can! Am I right, Noisy? He knows all about it. And here, something strange happens. Noisy, give us the sound of traffic, please. It’s just 10 dB louder than a normal conversation,
but I swear it sounds like something ten times louder than that! This is because our ears aren’t precise
instruments of sound perception. In reality, they’re constantly working in
tandem with our brains, forming a way to adapt sounds to be convenient for our hearing. As I already said, the key definition of a
sound’s loudness is in its pitch and intensity. We’re naturally programmed to hear high
pitched sounds as if they were louder than others. And anyone who has an annoying alarm waking
them up in the morning can tell you that! This a natural adaptation that makes it easier
for us to react to the high-pitched sound of a baby crying; it’s an uncontrollable
reaction of our mind to find the source of the high pitched sound, like the baby, and
make sure that it’s not a distress call. We also don’t perceive intensity as it actually
is. If you raise the intensity of any sound, it
won’t make any difference to your ear until a certain point. It’s easy to represent this way: Noisy,
please give us the traffic noise once again. Now make it sound like 10 different streets
with traffic around us. Yeah, that’s enough, Noisy, thank you. The sound just doubled its volume. It’s called the rule of thumb for loudness:
If the source of the sound is multiplied by 10, it’ll sound only twice as loud to our
ears. They don’t detect minor changes in volume;
this is the reason why it’s easier for us to measure sound in decibels, which is the
same as 10 bels. A change from 60 dB to 61dB just won’t make
any difference to us at all. Noisy, do you know any piano melodies? Yeah, perfect! And now, show us how loud a roaring truck
is. Thank you! Both things you’ve just heard are normally
around 80dB. They have the same level of loudness, but
one is pleasant to us and another is barely tolerable! This is another quirk of our hearing that
proves that we don’t just have a couple of microphones in our head, but a complex
system that can adjust the loudness of any sound depending on how we perceive it. But here comes the point where another fluke
happens in our perception. At 100 dB, the intensity won’t matter, whether
it’s a trombone, an elephant trumpeting, or a helicopter –they’d all sound equally
loud because we’re getting closer to our limit. Noisy, don’t take it personally, but can
you present all the following sounds to us from inside this semi-soundproof chamber? The safety limit of our ears is situated at
around 120 dB. Any sound beyond that would be painful to
hear at a close distance. These are sounds like the cymbal crash in
a band, a police siren, or a jet plane taking off from the ground. But there are a lot of sounds that lie in
that dangerous territory that we can explore. For example, in the animal world, there’s
no species louder than a sperm whale. This majestic creature can produce a series
of sounds at the astonishing level of 230 dB. No human being could bear this much noise
– it’s far beyond our reach of perception. This sound can travel for 10 miles underwater,
and it’d be a good idea to stay out of its range. Another underwater animal that can literally
stun with the sound it makes is the tiger-pistol-shrimp. Yep, from one of the biggest animals in the
history of our planet to one of the smallest. But it isn’t called pistol-shrimp for nothing. In fact, it’s louder than its namesake. This shrimp can clap his claw and shoot a
stream of water so powerful that it creates a bubble with a high force, which, when it
pops at 200 dB, will stun every fish within a 6.5ft radius. And then they’ll probably get eaten for
lunch. The loudest sound ever registered on our planet
was the sound of the Krakatoa volcano eruption in 1883. The sound waves from this explosive event
went around the whole Earth 4 times, and were clearly audible 3,000 miles away from the
volcano itself. Even Noisy gets a little scared when we’re
getting to this part of the excursion. Still, there are even greater powers in our
universe than this one. There was a sound detected that’s as powerful
as 100 million supernova explosions. And don’t even try to ask Noisy to make
this noise out loud. He can, but he won’t, because he doesn’t
want our planet to explode. Normally it’s quite hard to tell how loud
objects in space are, because in the vacuum of cosmos, there might only be very thin gas
that can’t transfer soundwaves. Except when we’re talking about a black
hole in the Perseus galaxy cluster. This monster can produce a sound that would
cover thousands of light-years around it, even if there’s little to no gas in this
space. Even a brave little robot like Noisy is scared
of this one! Hey, if you learned something new today, then
give the video a like and share it with a friend! And here are some other videos I think you'll
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on the Bright Side of life!
