RandomGuy
07-08-2016, 08:16 AM
http://fivethirtyeight.com/features/the-loudest-sound-in-the-world-would-kill-you-on-the-spot/
The questions kids ask about science aren’t always easy to answer. Sometimes, their little brains can lead to big places adults forget to explore. With that in mind, we’ve started a series called Science Question From a Toddler, which will use kids’ curiosity as a jumping-off point to investigate the scientific wonders that adults don’t even think to ask about. The answers are for adults, but they wouldn’t be possible without the wonder only a child can bring. I want the toddlers in your life to be a part of it! Send me their science questions and they may serve as the inspiration for a column. And now, our toddler …
Q: I want to hear what the loudest thing in the world is!
https://espnfivethirtyeight.files.wordpress.com/2016/07/20160706-1808-recording.mp3
No. No, you really don’t. See, there’s this thing about sound that even we grown-ups tend to forget — it’s not some glitter rainbow floating around with no connection to the physical world. Sound is mechanical. A sound is a shove — just a little one, a tap on the tightly stretched membrane of your ear drum. The louder the sound, the heavier the knock. If a sound is loud enough, it can rip a hole in your ear drum. If a sound is loud enough, it can plow into you like a linebacker and knock you flat on your butt. When the shock wave from a bomb levels a house, that’s sound tearing apart bricks and splintering glass. Sound can kill you.
Consider this piece of history: On the morning of Aug. 27, 1883, ranchers on a sheep camp outside Alice Springs, Australia, heard a sound like two shots from a rifle. At that very moment, the Indonesian volcanic island of Krakatoa was blowing itself to bits 2,233 miles away. Scientists think this is probably the loudest sound humans have ever accurately measured. Not only are there records of people hearing the sound of Krakatoa thousands of miles away, there is also physical evidence that the sound of the volcano’s explosion traveled all the way around the globe multiple times.
Now, nobody heard Krakatoa in England or Toronto. There wasn’t a “boom” audible in St. Petersburg. Instead, what those places recorded were spikes in atmospheric pressure — the very air tensing up and then releasing with a sigh, as the waves of sound from Krakatoa passed through. There are two important lessons about sound in there: One, you don’t have to be able to see the loudest thing in the world in order to hear it. Second, just because you can’t hear a sound doesn’t mean it isn’t there. Sound is powerful and pervasive and it surrounds us all the time, whether we’re aware of it or not.
In general, our world is much more crowded than we think it is. We all live life like we’re Maria von Trapp, swinging our arms around in an empty field. In reality, we’re more like commuters on the subway at 5 p.m. — hemmed in in every direction by the molecules that make up the air around us. Snap your fingers and you jostle the particles right next to you. As they wiggle, they bump into the particles next to them, which, in turn, nudge the particles next to them.
These wiggles are what the world’s barometers were measuring in the wake of the Krakatoa eruption. Again, think of being on a crowded train car. If you were to hip check the person standing next to you — which I do not recommend — they would tense up and scoot away from you. In the process, they’d probably bump into the next person, who would tense up and shimmy away from them. (There would also be words exchanged, but that is neither germane to our thought experiment nor child friendly.) Meanwhile, though, that original person you bumped into has now relaxed. The pattern travels through the crowd — bump-tense-wiggle-sigh, bump-tense-wiggle-sigh.
That’s what a sound wave looks like. It’s also why you can’t hear sounds in space. Being in a vacuum is like being in an empty subway car — there’s no molecular medium for the pattern of movement, tension and release to travel through. Likewise, sound travels a bit differently in water than it does in air, because the molecules in water are more tightly packed — a Tokyo subway car compared to one in New York.
For instance, the loudest animal on Earth might, in fact, live in the ocean. Sperm whales use echolocation to navigate, similar to what bats use — they make a clicking sound and can figure out what’s around by the way that sound wave bounces off objects and returns to them. A sperm whale’s click is 200 decibels, the unit used to measure the intensity of a sound, said Jennifer Miksis-Olds, associate professor of acoustics at Penn State. To give you a sense of the scale, the loudest sound NASA has ever recorded was the first stage of the Saturn V rocket, which clocked in at 204 decibels.
But the whale is not really as loud as the rocket, she told me. Because water is denser than air, sound in water is measured on a different decibel scale. In air, the sperm whale would still be extremely loud, but significantly less so — 174 decibels. That’s roughly equivalent to the decibel levels measured at the closest barometer, 100 miles away from the Krakatoa eruption, and is loud enough to rupture people’s ear drums. Suffice to say, you probably don’t want to spend a lot of time swimming with the sperm whales.
...
(read rest at link above)
(edit to add author)
Maggie Koerth-Baker is a senior science writer for FiveThirtyEight.
The questions kids ask about science aren’t always easy to answer. Sometimes, their little brains can lead to big places adults forget to explore. With that in mind, we’ve started a series called Science Question From a Toddler, which will use kids’ curiosity as a jumping-off point to investigate the scientific wonders that adults don’t even think to ask about. The answers are for adults, but they wouldn’t be possible without the wonder only a child can bring. I want the toddlers in your life to be a part of it! Send me their science questions and they may serve as the inspiration for a column. And now, our toddler …
Q: I want to hear what the loudest thing in the world is!
https://espnfivethirtyeight.files.wordpress.com/2016/07/20160706-1808-recording.mp3
No. No, you really don’t. See, there’s this thing about sound that even we grown-ups tend to forget — it’s not some glitter rainbow floating around with no connection to the physical world. Sound is mechanical. A sound is a shove — just a little one, a tap on the tightly stretched membrane of your ear drum. The louder the sound, the heavier the knock. If a sound is loud enough, it can rip a hole in your ear drum. If a sound is loud enough, it can plow into you like a linebacker and knock you flat on your butt. When the shock wave from a bomb levels a house, that’s sound tearing apart bricks and splintering glass. Sound can kill you.
Consider this piece of history: On the morning of Aug. 27, 1883, ranchers on a sheep camp outside Alice Springs, Australia, heard a sound like two shots from a rifle. At that very moment, the Indonesian volcanic island of Krakatoa was blowing itself to bits 2,233 miles away. Scientists think this is probably the loudest sound humans have ever accurately measured. Not only are there records of people hearing the sound of Krakatoa thousands of miles away, there is also physical evidence that the sound of the volcano’s explosion traveled all the way around the globe multiple times.
Now, nobody heard Krakatoa in England or Toronto. There wasn’t a “boom” audible in St. Petersburg. Instead, what those places recorded were spikes in atmospheric pressure — the very air tensing up and then releasing with a sigh, as the waves of sound from Krakatoa passed through. There are two important lessons about sound in there: One, you don’t have to be able to see the loudest thing in the world in order to hear it. Second, just because you can’t hear a sound doesn’t mean it isn’t there. Sound is powerful and pervasive and it surrounds us all the time, whether we’re aware of it or not.
In general, our world is much more crowded than we think it is. We all live life like we’re Maria von Trapp, swinging our arms around in an empty field. In reality, we’re more like commuters on the subway at 5 p.m. — hemmed in in every direction by the molecules that make up the air around us. Snap your fingers and you jostle the particles right next to you. As they wiggle, they bump into the particles next to them, which, in turn, nudge the particles next to them.
These wiggles are what the world’s barometers were measuring in the wake of the Krakatoa eruption. Again, think of being on a crowded train car. If you were to hip check the person standing next to you — which I do not recommend — they would tense up and scoot away from you. In the process, they’d probably bump into the next person, who would tense up and shimmy away from them. (There would also be words exchanged, but that is neither germane to our thought experiment nor child friendly.) Meanwhile, though, that original person you bumped into has now relaxed. The pattern travels through the crowd — bump-tense-wiggle-sigh, bump-tense-wiggle-sigh.
That’s what a sound wave looks like. It’s also why you can’t hear sounds in space. Being in a vacuum is like being in an empty subway car — there’s no molecular medium for the pattern of movement, tension and release to travel through. Likewise, sound travels a bit differently in water than it does in air, because the molecules in water are more tightly packed — a Tokyo subway car compared to one in New York.
For instance, the loudest animal on Earth might, in fact, live in the ocean. Sperm whales use echolocation to navigate, similar to what bats use — they make a clicking sound and can figure out what’s around by the way that sound wave bounces off objects and returns to them. A sperm whale’s click is 200 decibels, the unit used to measure the intensity of a sound, said Jennifer Miksis-Olds, associate professor of acoustics at Penn State. To give you a sense of the scale, the loudest sound NASA has ever recorded was the first stage of the Saturn V rocket, which clocked in at 204 decibels.
But the whale is not really as loud as the rocket, she told me. Because water is denser than air, sound in water is measured on a different decibel scale. In air, the sperm whale would still be extremely loud, but significantly less so — 174 decibels. That’s roughly equivalent to the decibel levels measured at the closest barometer, 100 miles away from the Krakatoa eruption, and is loud enough to rupture people’s ear drums. Suffice to say, you probably don’t want to spend a lot of time swimming with the sperm whales.
...
(read rest at link above)
(edit to add author)
Maggie Koerth-Baker is a senior science writer for FiveThirtyEight.