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What a crappy article. Apparently the answer is "it depends" but they're pretty sure it is "many kilometers". > In fact, hydrophones, or underwater microphone

What a crappy article. Apparently the answer is "it depends" but they're pretty sure it is "many kilometers". > In fact, hydrophones, or underwater microphones, if placed at the proper depth, can pick up whale songs and manmade noises from many kilometers away.

gmueckl 6y ago
This seems like a contradiction, but it isn't. Sound attenuation in sea water is extremely dependent on frequency. It is roughly a power law. Very low frequencies can easily travel extreme distances (0.001dB/km for 0.1Hz or so), but higher frequencies are attenuated more drastically. Whale song and man made noises have much higher frequencies. A quick Google search claims whale songs are around 80Hz to 4kHz. Absorption is around the 10 to 100dB/km range for 100Hz to 1kHz. So both statements in the article are true.
jessep 6y ago
Disagree! The article explains something extremely cool: that there’s a layer in the ocean that acts like a megaphone, where sound that passes into it gets caught and propagates way further. That’s cool and specific.
- koheripbal 6y ago
  Megaphones Amplify sound. Your analogy doesnt work. In no layer of the ocean is sound amplified.
  - kube-system 6y ago
    Electric megaphones amplify sound. Acoustic megaphones direct sounds, much like what the article describes.
    - jessep 6y ago
      Yeah, I was thinking about the old fashioned cheerleading things, without any electricity involved. I even thought about being explicit in case someone was going to be pedantic ... there’s even an emoji for it
OnlyOneCannolo 6y ago
An example would have been nice. It's old technology now, but here's an example of listening across the Atlantic. https://en.m.wikipedia.org/wiki/SOSUS https://en.m.wikipedia.org/wiki/SOSUS https://youtu.be/R462zEQ6RQA https://youtu.be/R462zEQ6RQA
rhodochrosite 6y ago
It depends is the real answer for any things. Understanding what it depends on is an important part of the discussion. Most people have no understanding of sound in the ocean. There is a ton of information at: https://dosits.org https://dosits.org - Discovery of Sound in the Sea. -Full disclosure, I am affiliated with that website.

gmueckl 6y ago

This seems like a contradiction, but it isn't. Sound attenuation in sea water is extremely dependent on frequency. It is roughly a power law. Very low frequencies can easily travel extreme distances (0.001dB/km for 0.1Hz or so), but higher frequencies are attenuated more drastically. Whale song and man made noises have much higher frequencies. A quick Google search claims whale songs are around 80Hz to 4kHz. Absorption is around the 10 to 100dB/km range for 100Hz to 1kHz. So both statements in the article are true.

jessep 6y ago

Disagree! The article explains something extremely cool: that there’s a layer in the ocean that acts like a megaphone, where sound that passes into it gets caught and propagates way further. That’s cool and specific.

koheripbal 6y ago
Megaphones Amplify sound. Your analogy doesnt work. In no layer of the ocean is sound amplified.
- kube-system 6y ago
  Electric megaphones amplify sound. Acoustic megaphones direct sounds, much like what the article describes.
  - jessep 6y ago
    Yeah, I was thinking about the old fashioned cheerleading things, without any electricity involved. I even thought about being explicit in case someone was going to be pedantic ... there’s even an emoji for it

OnlyOneCannolo 6y ago

An example would have been nice. It's old technology now, but here's an example of listening across the Atlantic. https://en.m.wikipedia.org/wiki/SOSUS https://en.m.wikipedia.org/wiki/SOSUS https://youtu.be/R462zEQ6RQA https://youtu.be/R462zEQ6RQA

rhodochrosite 6y ago

It depends is the real answer for any things. Understanding what it depends on is an important part of the discussion. Most people have no understanding of sound in the ocean. There is a ton of information at: https://dosits.org https://dosits.org - Discovery of Sound in the Sea. -Full disclosure, I am affiliated with that website.