Ah - past a certain range sound is "too far" and just doesn't play, yeah. It's based on the distance from the center of the screen; around 1800 "pixels" at the default zoom level for destroyers and frigates. So I guess that'd feel like right around the size you're describing if zoomed out a bit.
However sometimes the ship I piloted would stuck in the cast away area if I get cornered or I try to corner an enmey and the screen don't seem to pan to the left or right side any further, I could not hear myself. I went through the settings config file and couldn't find anything related to the sound range you mentioned, maybe in the next version you can make it a configurable varible or make the range bind to the widest or highest screen resolution.