
Does Military Sonar Kill Marine Wildlife? (2009) - turrini
http://www.scientificamerican.com/article/does-military-sonar-kill/
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andy_ppp
Why can the military not just use a different frequency that animals can't
hear? This whole thing sounds like a classic human failure; its under water,
we can't see it, who cares. The same goes for green house gases and allowing
oil companies to mess up countries like Nigeria.

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xjwm
In this case, it isn't the frequency that is the killer so much as the decibel
level. High frequency or low frequency, 235 Db is a lot of energy being
emmitted. In addition, the higher frequency of the sonar, the more quickly the
sound tends to attenuate, which is why the lower and medium frequencies work
best for those sensors.

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entheon
The weird part, though, is that I can't find any articles about how such
sounds might affect other things.

Like, what if a team of SCUBA divers had these high powered megawatt level
infra-sound transducers aimed directly at them, and felt the brunt of such a
wavefront at close range?

Would they even hear it, or maybe just feel it? Would they get a concussion?
Would it shake them so violently that maybe they suffer massive full-body
bruising, and even hemorrhaging or worse?

This is the part that seems unclear. How do these noises compare to something
like the shockwave of a depth charge, in terms of energy imparted on other
objects suspended in proximity? What happens to, oh I dunno, fine structured
ballistics gel replicas of sensitive organs?

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xjwm
Having spoken with Navy divers on thia issue, it could range from unpleasent
to fatal depending on how loud the active is, and distance from the
transducer. Before a dive, verifing that no ships nearby were planning on
transmitting was a required safety precaution. Someone smarter than me could
probably figure out what dB level actually causes internal damage.

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Rifu
A cursory google search gives the number 170dB as potentially fatal. [0]

[0]
[https://www.reddit.com/r/NoStupidQuestions/comments/30xga2/i...](https://www.reddit.com/r/NoStupidQuestions/comments/30xga2/if_a_sound_of_500db_goes_off_for_lets_say_0001/)

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entheon
That description is lackluster.

A train horn is 130, okay, we've all been too close to a train horn, and it's
unpleasant. But everything else in that reply is hypothetical, with not even
serious, realistic, testable anecdotes to support the claims.

Without supporting evidence all it says is:

    
    
      150 db is bad. 
      160 db is bad.
      170 db is bad.
      194 db is bad.
      185 db is bad. (tornados)
      220 db is bad. (bombs)
      250 db is bad. (bombs)
      310 db is bad. (volcanos)
      325 db is bad. (stratovolcano)
      500 db is bad.
    

Lots of "*beavis, that would be cool!" and not much else.

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pvaldes
Yes

