I was watching an episode of Mythbusters last night, and they were experimenting on making a noise in a car loud enough to destroy the car. They were mentioning decibel ratings, and how XX decibles is loud traffic, XX decibles is a jet engine, and ~200 decibels is loud enough to kill a person :eek:
Is this really true? I was laughing when they mentioned it, because it reminded me of an episode of Venture Brothers where Jonas Jr. is working on a Sound that Kills. But I didn’t realize loud noises could actually kill you!
~200DB is enough to pull the air right out of your lungs and give your organs some serious pounding.
That said, it takes a pretty huge amount of energy to create compressions that strong in mere air. And if you had such a machine, it would be pretty difficult to aim with any kind of precision.
Here’s a list with some example accoustic dB levels. Note that once you get up to around 180 or so, you start talking about large explosions rather than a Who concert.
The Mythbusters caused structural damage to a car made of steel with around 160 dB. I have no difficulty at all in believing that a soft and squishy human can be physically damaged by sufficiently loud sound.
Do you suppose that it’s just a coincidence that Cecil cites the 200 dB figure and then the same number appears on Mythbusters, whose newest researcher is our own Q.E.D.? Even if Q.E.D. was not directly responsible (chances are that episode was produced before he started with them), it’s obvious that the MB research staff reads SD.
Regarding that episode, I had heard about those extreme car audio competitions, so I was really pleased that MB included them in their coverage. The cars are essentially undriveable, and the sound systems in them are useless for standard music reproduction. The whole point is to create the highest sound pressure level inside the car when playing a brief LF “burp.” It’s crazy.
However, I was disappointed that Adam and Jamie didn’t come up with a somewhat more robust mechanical subwoofer. Theirs just tore itself apart in a few seconds. There are real subwoofers that use rotary drive systems instead of ordinary voice coils, albeit on a much smaller scale. So the principles are known, and I’m sure that with a little more effort they could have built something that would have lasted longer.
For reference, 200 dB SPL is around 29 psi. Check this Wikipedia article to check my math. Also remember that this is the root mean square pressure of the wave, so the peak pressure is around 41 psi, and the peak to peak change in pressure is 82 psi, which is quite a change for anyone to be able to withstand, especially when the sound is a higher frequency and cycling faster.
Of course, I don’t think there is a speaker out there that can produce this kind of volume, especially at the higher frequencies.
Wul, it seems to me that if a noise killed you, then it was both loud enough AND close enough.
I seem to recall reading something about how the Nazis were trying to develop a sonic cannon during WWII; it never came to anything due to the limited range… but ANY sound involves vibration; even a whisper shakes the air.
Focus that shaking air on a point, and you may have something.
Shake enough air hard enough, and you may have something more.
Build it to a tidal wave moving at the speed of sound, and you have a weapon.
The Nazis failed because theirs lacked range and portability; artillery was more mobile, easier to aim, and more accurate.
I remember reading an article about some mad professor type who was experimenting with giant organ pipes powered by a jet engine or similar. He was getting down to low enough frequencies with sufficient power to cause acute physical discomfort at quite a distance, or internal injuries at close range. Basically the soundwaves pretty much shook your guts to a pulp, even though you couldn’t actually hear anything. I did turn up an article from Princeton on Sonic Weapons (warning! PDF!) that gos into some detail, if you are interested.
Based on the responses so far, it appears that it’s not the sound that kills, it’s the movement of air. So even a deaf person would die from an extremely loud sound, even if he can’t hear it. Is that right?
Isn’t is something to do with the sound waves making your internal organs shake? Thereby it’s not how loud a noise, but what type of noise - I remember a few years back there was a choon in the charts that had a back beat that literally made me physically sick when it was played on the radio…
I seem to remember Brainiac (a UK show a bit like Mythbusters but not as kewl) playing “brown noise” that was supposed to make your bowel evacuate - they warned you first - I turned the sound off just in case (cite above example) apparently it did work and some people had to make a run for the loo