4 ms·

According to Wikipedia, the issue is with (low frequency, active) LFA sonar. https://en.m.wikipedia.org/wiki/Cetacean_stranding https://en.m.wikipedia.org/wiki

According to Wikipedia, the issue is with (low frequency, active) LFA sonar. https://en.m.wikipedia.org/wiki/Cetacean_stranding https://en.m.wikipedia.org/wiki/Cetacean_stranding I read somewhere it's about 240db. For reference, a jackhammer at about 1m (3.3ft away) is 130db and is classified as Painful for humans, http://www.asha.org/public/hearing/Noise/ http://www.asha.org/public/hearing/Noise/ I am not knowledgeable on acoustics, let alone acoustic dissipation or acoustics in water - but I can see logic behind the argument that LFA sonar causes a problem for whales.

nitrogen 11y ago
Also keep in mind that decibels are logarithmic, so 240dB is 10^(24-13) times as much sound power as 130.
- jleader 11y ago
  No, you forgot that the d stands for deci (i.e., 1/10th). So 240dB is 10^(2.4-1.3) times as much sound power as 130dB.
  - vonmoltke 11y ago
    No, nitrogen's math is correct. The conversion from linear to dB is y = 10 * log(x) and the conversion back is x = 10 ^ (y/10) Every change of 3dB is a doubling or halving of power. Every change of 10dB is an order-of-magnitude change in power.
    - nitrogen 11y ago
      Right, I did 24-13 instead of 240-130. That's 100 billion times the power.
    - jleader 11y ago
      D'oh! Thanks for catching my error!
dantillberg 11y ago
I did a little digging, and it seems that it's not really appropriate to compare underwater decibel measurements with decibel measurements in air. For example, [0] discusses whales that generate clicks at 230 dB, and suggests that that is "equivalent to 170 decibels on land." I'm not sure if it's even possible to get to 240 dB in air... Ah, an article on wikipedia sort of backs me up: [1] says that, at 1 atmosphere of pressure in air, the maximum loudness for undistorted sound is around 194 dB. Anything louder would be a shockwave. [0]: http://news.nationalgeographic.com/news/2003/11/1103_031103_tvspermwhale.html http://news.nationalgeographic.com/news/2003/11/1103_031103_... [1]: https://en.wikipedia.org/wiki/Sound_pressure https://en.wikipedia.org/wiki/Sound_pressure

nitrogen 11y ago

Also keep in mind that decibels are logarithmic, so 240dB is 10^(24-13) times as much sound power as 130.

jleader 11y ago
No, you forgot that the d stands for deci (i.e., 1/10th). So 240dB is 10^(2.4-1.3) times as much sound power as 130dB.
- vonmoltke 11y ago
  No, nitrogen's math is correct. The conversion from linear to dB is y = 10 * log(x) and the conversion back is x = 10 ^ (y/10) Every change of 3dB is a doubling or halving of power. Every change of 10dB is an order-of-magnitude change in power.
  - nitrogen 11y ago
    Right, I did 24-13 instead of 240-130. That's 100 billion times the power.
  - jleader 11y ago
    D'oh! Thanks for catching my error!

dantillberg 11y ago

I did a little digging, and it seems that it's not really appropriate to compare underwater decibel measurements with decibel measurements in air. For example, [0] discusses whales that generate clicks at 230 dB, and suggests that that is "equivalent to 170 decibels on land." I'm not sure if it's even possible to get to 240 dB in air... Ah, an article on wikipedia sort of backs me up: [1] says that, at 1 atmosphere of pressure in air, the maximum loudness for undistorted sound is around 194 dB. Anything louder would be a shockwave. [0]: http://news.nationalgeographic.com/news/2003/11/1103_031103_tvspermwhale.html http://news.nationalgeographic.com/news/2003/11/1103_031103_... [1]: https://en.wikipedia.org/wiki/Sound_pressure https://en.wikipedia.org/wiki/Sound_pressure