Originally Posted by Schroeder

I don't know. Did they constantly listen while steaming through the Atlantic? I think you can only hear things clearly when going rather slow (there are plenty of background noises in RL that aren't integrated in SH3 and 4). I guess that they were only listening when they thought that a U-Boat was near by. That would give us the option to strike first without warning. After they are alerted they should be able to detect torpedoes but not until then.