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Theoretical limit for loud music??

Discussion in 'Electronic Design' started by martin griffith, Sep 3, 2004.

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  1. from a post in pro.

    NEW YORK (Reuters Health) - Blasting music can be hard on the ears and
    the neighbors, and now researchers say it can also pack enough punch
    collapse a lung.

    Reporting in the medical journal Thorax, they describe the cases of
    young men who suffered a lung collapse -- technically called
    pneumothorax --that appeared to be triggered by loud music. Three of
    men were at a concert or club when the pneumothorax occurred, while
    fourth was in his car, which was outfitted with a 1,000-watt bass box
    because he "liked to listen to loud music."


    Serious error.
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  2. Tony

    Tony Guest

    .... none of which would however come even close to the "theoretical
    limit for loud music" (which is when the peak negative pressure gets
    down to a perfect vacuum - somewhere around 180dB SPL if memory
    Tony (remove the "_" to reply by email)
  3. I know I should have said Human limit.....
    Imagine 20Hz sine wave that goes from a vacuum to 2 atmos. More like a
    hurricane than music.

    But I dont think you could actaully hear the negative bottom part of
    the cycle, since sound doesn't travel through a vacuum!


    Serious error.
    All shortcuts have disappeared.
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  4. Rolavine

    Rolavine Guest

    Subject: Re: Theoretical limit for loud music??
    Nice thought, so if you were in a pressurized chamber you could get louder. I
    can see it now, car pressurization systems for louder music. Seeing bugged eyed
    teenagers clawing at the windows and looking desperate.

    I'm working on a new super sub woofer that uses a patented switchable
    containment field around a quantum black hole for Bass you can really feel. If
    we can only stop it from digesting the suburban kids and the new Honda Civic
    their rich parents bought them. Oh well, small loss.

  5. John Larkin

    John Larkin Guest

    There's no limit on the positive-direction overpressure, if you don't
    mind a bit of harmonic distortion (and who would, when you're being
    homogenized to death.)

  6. Frank Miles

    Frank Miles Guest

    Of course, it takes a _lot_ of energy to create extremely loud sound.
    There was once a study of how loud sound affects various ear structures;
    to get adequate sound levels, some experimental animals (think it was
    in rats) were anaesthatized in cages in close proximity to the space shuttle
    rocket boosters. IIRC the sound of the boosters when they were later
    fired was still below the 180dB mentioned in another posting. {Even
    that was not enough -- at least in those animals -- to collapse lungs.}

  7. Technical point. Actually, there is a maximum pressure. High pressure
    means high velocity, and this is limited, to yes.. the speed of light.

    Kevin Aylward
    SuperSpice, a very affordable Mixed-Mode
    Windows Simulator with Schematic Capture,
    Waveform Display, FFT's and Filter Design.
  8. John Larkin

    John Larkin Guest

    Oh, how could I have been so wrong!


    (hangs head in shame)
  9. 194 dB SPL, if the air pressure is 1 bar.
  10. I read in that Frank Miles <>
    No, it isn't. What happens, as explained in the original article, is
    that a small weakness in the lung wall ruptures under the intense sound
    pressure and allows air into the chest cavity. It is this air that
    causes the lung to collapse, if untreated for long enough (e.g. 30
  11. Guy Macon

    Guy Macon Guest

    John Larkin says...
    I am not sure that you were wrong. SPL is a function of the
    velocity and the mass of the medium. Unlike the negative limit
    which is hard clipping at zero pressure (vacuum), approaching
    the positive limit is a matter of pouring more and more energy
    into attempting to accelerate the medium, only to have that
    energy turn into mass rather than velocity at the E=MC2 rate.
    This additional mass allows higher pressures, and can approach
    infinity if you pump enough energy in.
  12. John Larkin

    John Larkin Guest

    Good point. I wonder what's the SPL close to one of those exploding

  13. Guy Macon

    Guy Macon Guest

    I can think of someone who I would like to send there with a Radio
    Shack SPL meter...
  14. Tony

    Tony Guest

    1800dB? what was I thinking? I always end up regretting it when I
    quote "hearsay" without working it out for myself! But now, having
    done that I feel I ought to point out that 0dB SPL is defined as 20uPa
    RMS (not peak), which means clipping starts around 191dB SPL at 1 bar.

    Tony (remove the "_" to reply by email)
  15. Don't feel in any way compelled to. (;-)

    Yes, you are quite right. Or would be if air were a perfect gas. We
    could go on like this, getting more and more refined, for no practical
  16. Yes, but technically its the momentum. Light has pressure, but no "rest
    That's not quite how it works though. This "mass increase" bit is a bit
    of a misnomer. Mass itself, doesn't actually increase. No professional
    physicist uses the concept at all, well, accept when writing popular

    Shit, now I have to go and think about when what gets applied to what,
    certainly this pops up (quick search) as an example:
    "The Heisenberg Uncertainty Principle also contains the seeds to setting
    a limit on how massive a white dwarf can be. Remember, nothing goes
    faster than light, so the maximum momentum of an electron is set by the
    speed of light and so there is a maximum pressure provided by degenerate
    electrons. This maximum sets the maximum mass that a white dwarf may

    This is one of those things that cropped up in class, now with the
    qualifiers forgotten. I'll have to do some more investigations as to
    when the limit applies...

    Kevin Aylward
    SuperSpice, a very affordable Mixed-Mode
    Windows Simulator with Schematic Capture,
    Waveform Display, FFT's and Filter Design.
  17. Robert Baer

    Robert Baer Guest

    And do not forget the compression of an H-bomb...
  18. Guy Macon

    Guy Macon Guest

    I thought we were talking about air approaching lightspeed.
    News to me - but then again, I am an eclectronicsite, not a Physicsoid..."mass+increases"
  19. "No practical advantage"? What better than to set the bar for
    Audiophools, in hopes they'll try to reach it?

    Mark L. Fergerson
  20. Sure, you'll find many references to "mass increase", but this is
    "inertial mass", a somewhat outdated term that is not very useful for
    serious work. For example, one gets into the bother of longitudinal mass
    and transverse mass, which are different. Mass is an invariant in

    have a look at

    or maybe :)

    Kevin Aylward
    SuperSpice, a very affordable Mixed-Mode
    Windows Simulator with Schematic Capture,
    Waveform Display, FFT's and Filter Design.
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