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SPL levels that can kill?

Discussion in 'Amps and Cabs [BG]' started by guyplaysbass, Feb 23, 2004.


  1. I know this is an odd one guys but I'm serious and was hoping that one of the "speaker gurus" on here might be able to give me a better understanding of SPL, decibels, etc... I have heard of competition car stereo systems that are literally capable of killing people. What I'm wondering is-

    A: Is this true?

    B: If it is then-

    What sound pressure levels are needed to theoretically kill or seriously injure human beings, fuzzy woodland creatures, etc...?

    What frequencies, and at what levels can/does this occur?

    How much power would be needed to achieve these levels?

    I'm having a disagreement with a fellow bassist who does not think these things are capable of happening. He is standing on the argument that if this was so people would be dropping dead at concerts all over the world. I would like to provide him with the actual physics, numbers, whatever... of the phenomena so that he might believe me. I will then construct a massive RIG-O-DEATH and travel the galaxy destroying all those who defy my wrath! Mwuu HA-AA-AA-AA! I mean, um... provide him with the math!

    Also, the formula to determine how loud a given speaker enclosure/design will get would be pretty awesome too.

    bgavin? :help:
     
  2. Metal Mitch

    Metal Mitch

    Jul 14, 2003
    NJ
    You won't be the only one! Weapons of Mass Destruction anyone? BUAHAHAHA!!!
     
  3. the inside of a car is much smaller that at a concert therefore it should be easier to reach a killing level. i saw sound that could crack through brick on tv a few years back it was pretty kickass
     
  4. The concussion from an explosion can kill you and it is a sound wave. I found this at Wikipedia:

    "Sounds above 85 dB are considered harmful, while 120 dB is unsafe and 150 dB causes physical damage to the human body. Windows break at about 163 dB. Jet airplanes are about 133 dBA at 33 m, or 100 dBA at 170m. Eardrums pop at 190 to 198 dB. Shock waves and sonic booms are about 200 dB at 330 m. Sounds around 200 dB can cause death to humans and are generated near bomb explosions (e.g. 23 kg of TNT detonated 3 m away). The space shuttle is around 215 dB (or about 175 dBA at 17m). Nuclear bombs are 240 dB to 258 dB (distance unknown). Even louder are earthquakes, tornados, hurricanes and volcanoes."

    You would probably have a hard time getting 200dB out of a speaker.

    Geoff
     
  5. Hey Guys,

    Many of the facts and figures quoted here are highly debatable and extremely inconsistant. Thought I don't wish to offend anyone, Geoff in particular, the only way a true comparison can be made between the SPL levels generated in the different situations described is if they are all measured from exactly the same distance, under the exact same environmental conditions, using the same equipment. That being said, yes sound waves definately can kill human beings and other forms of life, as a sound wave is a merely an oscillating pressure wave and the concussion from a pressure wave will certainly damage your body.

    The threshold of feeling, i.e. the point at which damage starts to occur to the human eardrum, is typically around 110dB but can vary from subject to subject. Whereas the threshold of pain, i.e. the point at which the eardrum can stand no more and begins to tear is typically 140dB. Both of these figures are stated as the SPL at the ear.

    The lesson to learn: but some decent earplugs and use them.

    Hope this helped!
    Lexy
     
  6. The 0x

    The 0x

    Aug 24, 2003
    Timonium, MD
    Well, I dunno about killing, but this rig was sure damn loud, at least as loud as a jet engine. :eek:
    [​IMG]

    :p

    But seriously, if you're gonna build a big rig of mass destruction, you'll need a roadie with that.
     
  7. MJ5150

    MJ5150 Terrific Twister

    Apr 12, 2001
    Lacey, WA
    I saw a show on Discovery channel that talked about the military using sound waves in warfare. The right frequencies can confuse people, and cause involuntary bowel movements.

    -Mike
     
  8. The 0x

    The 0x

    Aug 24, 2003
    Timonium, MD
    [​IMG]

    I gotta scope that out on kazaa.
     
  9. Mcrelly

    Mcrelly

    Jun 16, 2003
    Minnesota, USA
    I've heard the who had the guiness world record for the loudest concert was 120 decibels at 46m I don't know what that traslates into AT THE SPEAKER, but I bet its more than 130!!!
    here is the link: http://www.thewho.org/photos.htm (top story)


     
  10. Wolfehollow

    Wolfehollow

    Jan 21, 2003
    Pensacola, FL
    apparently when the blimps would fly over the trenches in WW1 the troops would vomit from the low oscillation of the props.
     
  11. Mcrelly

    Mcrelly

    Jun 16, 2003
    Minnesota, USA
    reminds me of school. one time our science teacher or someone arraged for a "jet-engine" to be demonstrated in the school gymnasium. I can't remember what it looked like clearly, but reminded me of the early goddard rocket motors? maybe not, but it was like a tank with a nozzle and when they fired it up produced a blue flame and made a terrible LOW LOW rumble that instantly hit me in the gut and almost made me throw up!!! they only ran it for a few seconds, but MAN!
     
  12. Nick man

    Nick man

    Apr 7, 2002
    Tampa Bay
    Im sure that its not too dificult to build a "death room" if you use enough speakers.

    I bet it could be done with less than 15K watts.

    Peace
    Nick
     
  13. The 0x

    The 0x

    Aug 24, 2003
    Timonium, MD
    Heh, you'll only need 3 of these:

    [​IMG]
     
  14. MJ5150

    MJ5150 Terrific Twister

    Apr 12, 2001
    Lacey, WA
    Who needs 5000 watts for a bass? There's no way someone could need that much power.

    -Mike
     
  15. Nick man

    Nick man

    Apr 7, 2002
    Tampa Bay
    Who said it would be for bass?

    Besides, I would believe that they could be useful in certain rigs.

    For instance, a world famous bassist doing large gigs for a very popular rock band who uses Acme cabs which are inefficient.

    Remeber that in order to double your volume (without adding speakers.) you need to multiply your wattage by 10. So thats only twice as loud as a 500 watt amp.

    Peace
    Nick
     
  16. MJ5150

    MJ5150 Terrific Twister

    Apr 12, 2001
    Lacey, WA
    I did! :D

    Yeah, I suppose that is for PA applications, or a gig at the Meadowlands.

    -Mike
     
  17. Petebass

    Petebass

    Dec 22, 2002
    QLD Australia
    This is a two sided answer. You notice that PA's generally have the mid and high frequency speakers elevated above ear level. There's a couple of reasons for that. It's partly because it would only take one or 2 people to stand in front and suddenly no-one else can hear those frequencies. The second reason is more relevent to this thread - a mid/high speaker at high SPL hurts your ears and sounds harsh. We used to joke that we should put em at ear level at those rough gigs where we don't particularly want people approaching the stage. As they walked towards us, it would feel more and more like they were sticking their head into a microwave .............

    However according to my Audiologist, those aren't the frequencies that damage your ears. Well they do, but the low frequencies are the ones that are capable of bursting ear drums. The danger of course is that our brains don't percieve those frequencies as painful to listen to. So when your car audio competitor runs from the car screaming and with blood in his ears, the poor bugger didn't see it coming.


    Remember that in a car, you're basically sitting inside the speaker cabinet. The cabin causes an increase in SPL. Put those car audio stsyems in the middle of a football field and they're nowhere near as loud, even if you stand the same distance away.

    So as you can see, the wattage will vary. But as a general guide, use this formula:-

    Max SPL = Sensitivity (dB) + 10(log (speaker watts RMS))

    So for example, You've got an Eden 4x10. It's 700 watts RMS and the sensitivity is 107dB at 1w/1m.

    Max SPL = 107+ 10(log 700)

    Max SPL = 135.451 dB

    Well it works with a 1k sine wave anyway. You'll find the speaker is several dB down at the frequencies needed to pop ear drums. BUt the theory still applies. So the get the same SPL from a less efficient speaker, you need more watts and/or more speakers.
     
  18. Sometimes when I play, folks hurl. I'd like to think it's the low oscillation, but the truth is it's my level of talent.
     
  19. thrash_jazz

    thrash_jazz

    Jan 11, 2002
    Ottawa, Ontario, Canada
    Artist: JAF Basses, Circle K Strings
    Those would be infrasonic frequencies (below 20 Hz).

    It'd be difficult to measure those, because they aren't audible.

    As far as SPL's go, as far as I know, a loud concert is 120 db or slightly above, 130 db is the pain threshold, 160 db will burst your eardrums (160 is also a Saturn rocket taking off nearby).

    Also, remember that the db scale is logarithmic - meaning 160 db contains 10,000 times more sound energy than 120 db.
     
  20. miccheck1516

    miccheck1516 Guest

    Feb 15, 2003
    Ireland
    You saw sound???? cool. :)