7 ms·

Nice. I hadn't thought of there being a limit (due to vacuum) to sound intensity. Reminds me of this recent comment on reddit: http://np.reddit.com/r/space/com

by jbert 12y ago

Nice. I hadn't thought of there being a limit (due to vacuum) to sound intensity. Reminds me of this recent comment on reddit: http://np.reddit.com/r/space/comments/2h9y9g/the_first_launch_from_cape_canaveral_1950/ckr6mev http://np.reddit.com/r/space/comments/2h9y9g/the_first_launc... "the Saturn V rocket produced a SWL (Sound Power Level) of about 220 decibels, which is sufficient to melt concrete nearby and set grass aflame a mile away,"

BrandonMarc 12y ago
Wait, the sound caused the grass to catch fire?!
- alex_duf 12y ago
  I guess that at this level "shockwave" is more correct than "sound"
- ars 12y ago
  Don't forget that compression causes gas to heat up.
- marcosdumay 12y ago
  A 220 dB sound is quite strong. As an example, its intensity (in W/solid angle) is 14 orders of magnitude (AKA 100 billion times) highter than the 80 dB people usualy use as a safety limit.
  - aruggirello 12y ago
    Are you sure? Shouldn't a 140 dB difference in intensity equate to just about 2^14, hence 16384 times stronger?
    - jrkatz 12y ago
      The decibel scale uses a log_10, not log_2.
  - astrodust 12y ago
    Saying "quite strong" here is like saying a thermonuclear explosion is "warm". Sound that loud wouldn't just kill you, it'd rip you apart.
    - abdulhaq 12y ago
      I think this is a US/UK English thing, in the US 'quite' only means 'very' whereas in the UK it often means 'a bit'. (I'm guessing your from the UK).
      - astrodust 12y ago
        Canadian, which does have a lot of British influence. Saying a burrito is "quite spicy" usually means "surprisingly" but not "excessively" or "extraordinarily".
        marcosdumay 12y ago
        I'm Brazilian. Those things are already too subtle and hard enough to learn in a second language. People defining the same expression with widely conflicting meanings in different places do literally turn it into a maze :)
        merrua 12y ago
        It should mean, you can't get it wrong, but instead it tends you mean, you are always wrong. Ah well.
- gumby 12y ago
  Indeed; this is the principle behind the fire piston http://en.wikipedia.org/wiki/Fire_piston http://en.wikipedia.org/wiki/Fire_piston
josu 12y ago
But the article says: "This limit happens to be about 194 decibels for a sound in Earth’s atmosphere." Therefore, wouldn't 220db be like -280°C? EDIT: Somewhat of an answer: 194.09(P) = 1 (ONE) AIR ATMOSPHERE = 14.6962 POUNDS PER SQUARE INCH = 14.6962 P.S.I.= 1 ATM SOUND WAVES DISTORT AND ARE NOW DEFINED AS SHOCK WAVES AND THEY BEGIN TO FOLLOW SHOCK WAVE BEHAVIOR. PARTICLE VELOCITY (BLAST WIND) = 590 FEET / SECOND = 180 METERS PER SECOND = 402 MILES PER HOUR. -REF.2. Source: http://www.makeitlouder.com/Decibel%20Level%20Chart.txt http://www.makeitlouder.com/Decibel%20Level%20Chart.txt
- ars 12y ago
  At that point it's not a sound anymore but rather a shockwave. Once it dissipates a bit it becomes a sound again.
- gambiting 12y ago
  -280C would be -7 Kelvin, and therefore impossible.
  - Moru 12y ago
    I think that was his point.
    - josu 12y ago
      Yeap
dandelany 12y ago
Yes! My favorite example of this is the sound made by the space shuttle's solid rocket boosters at liftoff. Techies who have seen recordings of shuttle launches generally assume the guttural crackling, popping roar sound they hear is due to a badly adjusted microphone clipping the loud sounds. In fact, this was a physical phenomenon that could be heard in real life, due to the pressure waves physically "clipping" against a vacuum upon reaching the atmospheric pressure limit! Sorry I can't seem to find any better sources, but this is an anecdote I've heard from several witnesses: http://forums.prosoundweb.com/index.php?topic=98023.25;wap2 http://forums.prosoundweb.com/index.php?topic=98023.25;wap2 Here's a good example of the sound I'm talking about: https://www.youtube.com/watch?v=OnoNITE-CLc&t=1m44s https://www.youtube.com/watch?v=OnoNITE-CLc&t=1m44s
- deleted 12y ago
  [deleted]
- malingo 12y ago
  Previous HN discussion about shuttle launches, with a very entertaining essay by Penn and Teller https://news.ycombinator.com/item?id=2793404 https://news.ycombinator.com/item?id=2793404
- disillusioned 12y ago
  I had the privilege of watching STS-134 launch from the press site and everyone tells you: "it's loud. louder than loud. you will be surprised by how loud it was." and that still wasn't enough to prepare me. It is loud. It is literally like the sound is clipping, the brapping noise moves through your teeth, it vibrates your clothes, you feel it inside of you. It is incredible, and I was so lucky to have watched it from the closest any humans are allowed to be (except for the brave rescue team in an APC 1 mile away).
  - marcosscriven 12y ago
    I recall being thrilled to be able to see STS-124 in May 2008, only because the previous launch had been delayed, and the new date coincided with our holiday. Among other things it was taking up parts to fix a toilet on the ISS! I remember also being struck by not only how loud it was, but also how bright. It's something that photos or video just can't capture.
Arjuna 12y ago
Speaking of the Saturn V... it's one of the most powerful machines that humans have ever created. It was equipped with five F-1 rocket engines, with each engine producing an absolutely staggering 1,500,000 pounds of thrust; that's a total of 7,500,000 pounds of thrust! Can you imagine being tucked into the small, cramped Command Module, sitting on top of this magnitude of power at lift-off? The whole thing, the technology, the sound, the people coming together to make it happen... it's soul-stirring. https://www.youtube.com/watch?v=ygBxN5UiOaM https://www.youtube.com/watch?v=ygBxN5UiOaM
- post_break 12y ago
  Standing next to the thing makes you feel like an ant. I visit it once and a while and I just think to myself "we did this, this thing blasted off of the face of the earth with humans at the top"
  - Toenex 12y ago
    This quote from John Glenn always reminds me just how brave those sons of bitches were; "As I hurtled through space, one thought kept crossing my mind - every part of this rocket was supplied by the lowest bidder."
    - techdragon 12y ago
      I cannot believe I have never heard this quote before. I literally LOLed.
- dingaling 12y ago
  > Speaking of the Saturn V... it's one of the most powerful machines that humans have ever created. In the interest of completeness, here are the two most powerful launchers even flown in terms of first-stage lift-off thrust N-1: 4,600 tonnes / 10 million lb Energia: 3,600 tonnes / 7.9 million lb Saturn V is currently in third place but will be pushed down if / when Falcon Heavy flies.
  - 12y ago
Shivetya 12y ago
following links within yours leads to http://www.makeitlouder.com/Decibel%20Level%20Chart.txt http://www.makeitlouder.com/Decibel%20Level%20Chart.txt which indicates that there were other volcanoes before measurement could be done that would have been more severe. Essentially telling us that one volcano could change our lives, if not end a substantial number of them.
dustyleary 12y ago
I almost commented on the reddit post at the time, but decided not to. Now that I see it repeated, I want to. This is a reading comprehension error, I think. I guess I'm not 100% sure. That "melting concrete and setting grass aflame" comes from the link, here: http://www.makeitlouder.com/Decibel%20Level%20Chart.txt http://www.makeitlouder.com/Decibel%20Level%20Chart.txt That link has many decibel levels, and examples, and factoids about the things producing the sound, unrelated to the sound itself. I think the chart intends to say that the rocket melts concrete, sets grass on fire 1 mile away, and produces sound that is 220 decibels. Not that the sound itself is melting concrete or setting grass on fire. The reddit post mentions "At 2 kilometers (140+ db), ..." 2km is a little more than 1 mile. So if the sound alone could set grass aflame a mile away, then that would mean that 140db at distance zero is enough set grass on fire. If it can set grass on fire, then it can set a lot of other things on fire. Paper, clothing, hair, etc... Some extremely loud rock concerts hit 150db. So, while I guess I'm not 100% sure that this is an error, I just doubt that rock concert speakers can/would output enough volume to set things right next to them on fire. There would be huge safety issues, and risk of the speakers destroying themselves and other equipment. I know nobody is right next to speakers this loud, but still... I doubt the accuracy of this 'melting concrete and setting grass aflame via sound' factoid. I would love to be shown wrong, because it is really interesting if it's true.

by jbert 12y ago

BrandonMarc 12y ago

Wait, the sound caused the grass to catch fire?!

alex_duf 12y ago
I guess that at this level "shockwave" is more correct than "sound"
ars 12y ago
Don't forget that compression causes gas to heat up.
marcosdumay 12y ago
A 220 dB sound is quite strong. As an example, its intensity (in W/solid angle) is 14 orders of magnitude (AKA 100 billion times) highter than the 80 dB people usualy use as a safety limit.
- aruggirello 12y ago
  Are you sure? Shouldn't a 140 dB difference in intensity equate to just about 2^14, hence 16384 times stronger?
  - jrkatz 12y ago
    The decibel scale uses a log_10, not log_2.
- astrodust 12y ago
  Saying "quite strong" here is like saying a thermonuclear explosion is "warm". Sound that loud wouldn't just kill you, it'd rip you apart.
  - abdulhaq 12y ago
    I think this is a US/UK English thing, in the US 'quite' only means 'very' whereas in the UK it often means 'a bit'. (I'm guessing your from the UK).
    - astrodust 12y ago
      Canadian, which does have a lot of British influence. Saying a burrito is "quite spicy" usually means "surprisingly" but not "excessively" or "extraordinarily".
      - marcosdumay 12y ago
        I'm Brazilian. Those things are already too subtle and hard enough to learn in a second language. People defining the same expression with widely conflicting meanings in different places do literally turn it into a maze :)
        merrua 12y ago
        It should mean, you can't get it wrong, but instead it tends you mean, you are always wrong. Ah well.
gumby 12y ago
Indeed; this is the principle behind the fire piston http://en.wikipedia.org/wiki/Fire_piston http://en.wikipedia.org/wiki/Fire_piston

josu 12y ago

But the article says: "This limit happens to be about 194 decibels for a sound in Earth’s atmosphere." Therefore, wouldn't 220db be like -280°C? EDIT: Somewhat of an answer: 194.09(P) = 1 (ONE) AIR ATMOSPHERE = 14.6962 POUNDS PER SQUARE INCH = 14.6962 P.S.I.= 1 ATM SOUND WAVES DISTORT AND ARE NOW DEFINED AS SHOCK WAVES AND THEY BEGIN TO FOLLOW SHOCK WAVE BEHAVIOR. PARTICLE VELOCITY (BLAST WIND) = 590 FEET / SECOND = 180 METERS PER SECOND = 402 MILES PER HOUR. -REF.2. Source: http://www.makeitlouder.com/Decibel%20Level%20Chart.txt http://www.makeitlouder.com/Decibel%20Level%20Chart.txt

ars 12y ago
At that point it's not a sound anymore but rather a shockwave. Once it dissipates a bit it becomes a sound again.
gambiting 12y ago
-280C would be -7 Kelvin, and therefore impossible.
- Moru 12y ago
  I think that was his point.
  - josu 12y ago
    Yeap

dandelany 12y ago

Yes! My favorite example of this is the sound made by the space shuttle's solid rocket boosters at liftoff. Techies who have seen recordings of shuttle launches generally assume the guttural crackling, popping roar sound they hear is due to a badly adjusted microphone clipping the loud sounds. In fact, this was a physical phenomenon that could be heard in real life, due to the pressure waves physically "clipping" against a vacuum upon reaching the atmospheric pressure limit! Sorry I can't seem to find any better sources, but this is an anecdote I've heard from several witnesses: http://forums.prosoundweb.com/index.php?topic=98023.25;wap2 http://forums.prosoundweb.com/index.php?topic=98023.25;wap2 Here's a good example of the sound I'm talking about: https://www.youtube.com/watch?v=OnoNITE-CLc&t=1m44s https://www.youtube.com/watch?v=OnoNITE-CLc&t=1m44s

deleted 12y ago
[deleted]
malingo 12y ago
Previous HN discussion about shuttle launches, with a very entertaining essay by Penn and Teller https://news.ycombinator.com/item?id=2793404 https://news.ycombinator.com/item?id=2793404
disillusioned 12y ago
I had the privilege of watching STS-134 launch from the press site and everyone tells you: "it's loud. louder than loud. you will be surprised by how loud it was." and that still wasn't enough to prepare me. It is loud. It is literally like the sound is clipping, the brapping noise moves through your teeth, it vibrates your clothes, you feel it inside of you. It is incredible, and I was so lucky to have watched it from the closest any humans are allowed to be (except for the brave rescue team in an APC 1 mile away).
- marcosscriven 12y ago
  I recall being thrilled to be able to see STS-124 in May 2008, only because the previous launch had been delayed, and the new date coincided with our holiday. Among other things it was taking up parts to fix a toilet on the ISS! I remember also being struck by not only how loud it was, but also how bright. It's something that photos or video just can't capture.

Arjuna 12y ago

Speaking of the Saturn V... it's one of the most powerful machines that humans have ever created. It was equipped with five F-1 rocket engines, with each engine producing an absolutely staggering 1,500,000 pounds of thrust; that's a total of 7,500,000 pounds of thrust! Can you imagine being tucked into the small, cramped Command Module, sitting on top of this magnitude of power at lift-off? The whole thing, the technology, the sound, the people coming together to make it happen... it's soul-stirring. https://www.youtube.com/watch?v=ygBxN5UiOaM https://www.youtube.com/watch?v=ygBxN5UiOaM

post_break 12y ago
Standing next to the thing makes you feel like an ant. I visit it once and a while and I just think to myself "we did this, this thing blasted off of the face of the earth with humans at the top"
- Toenex 12y ago
  This quote from John Glenn always reminds me just how brave those sons of bitches were; "As I hurtled through space, one thought kept crossing my mind - every part of this rocket was supplied by the lowest bidder."
  - techdragon 12y ago
    I cannot believe I have never heard this quote before. I literally LOLed.
dingaling 12y ago
> Speaking of the Saturn V... it's one of the most powerful machines that humans have ever created. In the interest of completeness, here are the two most powerful launchers even flown in terms of first-stage lift-off thrust N-1: 4,600 tonnes / 10 million lb Energia: 3,600 tonnes / 7.9 million lb Saturn V is currently in third place but will be pushed down if / when Falcon Heavy flies.
- 12y ago

Shivetya 12y ago

following links within yours leads to http://www.makeitlouder.com/Decibel%20Level%20Chart.txt http://www.makeitlouder.com/Decibel%20Level%20Chart.txt which indicates that there were other volcanoes before measurement could be done that would have been more severe. Essentially telling us that one volcano could change our lives, if not end a substantial number of them.

dustyleary 12y ago

I almost commented on the reddit post at the time, but decided not to. Now that I see it repeated, I want to. This is a reading comprehension error, I think. I guess I'm not 100% sure. That "melting concrete and setting grass aflame" comes from the link, here: http://www.makeitlouder.com/Decibel%20Level%20Chart.txt http://www.makeitlouder.com/Decibel%20Level%20Chart.txt That link has many decibel levels, and examples, and factoids about the things producing the sound, unrelated to the sound itself. I think the chart intends to say that the rocket melts concrete, sets grass on fire 1 mile away, and produces sound that is 220 decibels. Not that the sound itself is melting concrete or setting grass on fire. The reddit post mentions "At 2 kilometers (140+ db), ..." 2km is a little more than 1 mile. So if the sound alone could set grass aflame a mile away, then that would mean that 140db at distance zero is enough set grass on fire. If it can set grass on fire, then it can set a lot of other things on fire. Paper, clothing, hair, etc... Some extremely loud rock concerts hit 150db. So, while I guess I'm not 100% sure that this is an error, I just doubt that rock concert speakers can/would output enough volume to set things right next to them on fire. There would be huge safety issues, and risk of the speakers destroying themselves and other equipment. I know nobody is right next to speakers this loud, but still... I doubt the accuracy of this 'melting concrete and setting grass aflame via sound' factoid. I would love to be shown wrong, because it is really interesting if it's true.