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cranial_prolapse420 t1_j6ig6c7 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

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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