Well after much experimenting I've discovered the following:
- I set up a mission with one stopped ship and me at 90 degrees to it, at 450 meters. Both Scufundare sound entries in the .sdl file were changed to 800 meters distance.
- using a stock install, I was able to hear the sinking sound in the command room, map view, external view, etc.
But ONLY with some ships. I.e., the large tanker has the sound, the C-2/3 ships do not.
So it would appear some trigger in each ship's sea folder files holds the answer though I've been unable to find it yet.
Anyway, I extended the scufundare vapor.wav to 3500 meters (I fire up to 4000 meters with the standard torpedoes) in my NYGM install and it works per the above limitations (only some ships).