Cold Waters Nuclear Submarine game/sim website by PMC.
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Baffles is area behind a submarine or a surface ship where the boats/ships own hull mounted sonar cannot hear, its the propeller blade bubbles or water disturbance that makes you deaf behind your own boat. Sorry I'm not an expert on this description but this is as best as I can remember and summarize it. PMCTODO. After writing this paragraph to here I googled it up, amazing how close I came from decades old memory, see Baffles (Submarine) wikipedia.
I believe the area is around 45 degrees behind your boat, a 45 degree cone of unable to hear anything.
Get into enemy subs/ships baffles to reduce or maybe even completely hide your weapon launch transient noise.
In Tom Clancy book and later movie The Hunt For The Red October, Marko Ramius checks his baffles every top of the hour to make sure no pesky Amerikansk capitalist pig nuke boat is not tailing his SSBN Typoon class :)
If enemy has towed array sonar then hiding in the baffles is not possible as towed array sonar will hear you directly behind the boat.