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iiSpook t1_j6hpmi5 wrote

Reply to comment by SamtheCossack in TIL that sperm whales are the loudest animal on Earth, and their clicks can literally kill you with sound by g1ucose

You got an approximate decibel value to make it easier to imagine?

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SamtheCossack t1_j6htcig wrote

Around 230, which is massively more than gunshots, jet engines, and even bomb explosions.

That said, decibels aren't really a good way of measuring sounds like that. It is a tightly focused long range sonar "Beam" that is used for scanning the ocean depths for prey, not a radial blast like the others mentioned. It is also in water, and compression effects in water are massively more dangerous, because the water doesn't compress like air is, so a human body gets hit by the full force.

So yeah, if a whale aimed it a human and did it at full force, it would kill the human. But they don't use it as a weapon, and the whale is very unlikely to do that. Especially since they seem to like people, and act curious and friendly to divers, and never hostile unless you spear them.

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iiSpook t1_j6hu4ul wrote

Oh, wow, I did indeed assume it was radial. So cool to hear they can actually precisely aim it. I do understand that you can't compare sound waves in water to air directly, I was just asking for a rough ballpark and you did deliver.

Follow-up question out if interest, if you allow. If I was next to one and they aimed the "beam" away from me, would I hear nothing or just a faint noise or something like that?

Thanks for your initial reply.

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SamtheCossack t1_j6hun5b wrote

If you were right next to it, I would assume it would be a very unpleasant experience. The force might be moving away from you, but the water won't stop moving once the sound goes through, and you would get a really nasty shockwave going through your body.

It would probably be a similar level of disorientation to being in a fairly high speed car crash.

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iiSpook t1_j6hv0sl wrote

Damn, that's so cool. Thanks, man.

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cranial_prolapse420 t1_j6ig6c7 wrote

Decibles are definitely used for measuring sound in a radius (or in this case, a free field). I'm curious to hear why you think it isn't a good way of measuring SPL, and which units you would use instead?

(I agree with everything else you said.)

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SamtheCossack t1_j6ih8j5 wrote

Mostly because it is in water.

Trying to compare decibels in air to decibels in water is not really a useful measurement of anything, since the nature of sound changes dramatically in different materials. Also, directed sound, like this, would only hit the peak amplitude in the exact center of the cone, and would drop off rapidly towards the edges, as opposed to a radial effect like an explosion, where it would be consistent across a wide front. This enables much higher amplitudes, but in an extremely small area, with a lot less energy overall.

So yeah, for a lot of reasons, saying gunshots are ~150 decibels, and Sperm Whales can hit 230 decibels is technically accurate, but not really what it sounds like. For instance, a pistol shrimp can hit ~220 decibels, but is almost completely harmless to anything bigger than a minnow, because it has such a short duration, and tiny scale.

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cranial_prolapse420 t1_j6im054 wrote

It's a unit of measurement used to express the ratio of one quantity to another. The medium has nothing to do with it.

To convert between dB in water and air, just subtract 26dB from the measured water SPL. This is necessary because sound measured in air uses a reference level of 20upa @ 1m, water has a reference level of 1upa @ 1m.

I'd also argue whale vocalizations are likely omnidirection, since it's a method of communication and would be pretty ineffective if you had to aim it across an ocean and hope someone happened to be on the receiving end.

Still wondering which unit you'd prefer to use?

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SamtheCossack t1_j6imhpy wrote

The 230 dB vocalizations are not for communication, they are for locating prey in the deep ocean. They are directed down, and used to locate the optimal location for the whales next dive. Communication clicks are considerably less energetic (Though still powerful).

I am not saying decibels aren't the right measurement, I am saying comparing the two on a 1 to 1 basis doesn't paint a useful picture of what is happening.

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cranial_prolapse420 t1_j6iv5os wrote

Fair enough, sorry to be a pendantic jackass. It's morning where I'm at; coffee had not yet occured.

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Zarmazarma t1_j6j26qh wrote

> Around 230, which is massively more than gunshots, jet engines, and even bomb explosions.

The conversion factor for sound intensity between air and water is approximately 62 decibels. This means a 230 decibel sound underwater is comparable to a 168 decibel sound above water. This is similar to a variety of gunshots going off about a meter from your ear (incidentally, also about the range you fire a gun from).

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