I’ll make it short: since sound travels four times as fast through water as it does through air, does a ship at sea “hear” distant explosions twice?
I was thinking you might hear the waterborne soundwave first, conducted through the hull, and then the airborne one a bit later. But I have no idea if that’s actually true. Can anyone fight my ignorance?
Well one thing I do know for certain, you set off an A/S mortar and you get the shockwave pretty good, and thats over a mile away, lord alone knows what it must be like in a sub in the vicinity - the ship feels like it has just hit a hole.
Not easy question to answer, when you are doing firing operations you have a clear fire zone, usually twice your weapon range and that means you are never really near enough to notice the effects from other ships, and when your own ship is doing the shooting, well there is no time gap at all.
Best placed to know would be the sonar operators, however their stuff is deep inside so they don’t get to see and hear weapon flash directly, but they would probaly have som eidea of the propagation of shockwaves through water.
I can speak to the 16" guns of the USS New Jersey from experience. We were in a combined fleet with them and got to watch the 16" guns fire.
On board the carrier, USS Ranger, we did not feel/hear the explosion through the hull before we heard the explosions through the air. On the carrier we did not feel the shots at all in fact.
I’m not sure that was what you meant, but seemed like a useful observation and might answer your question.