Reddit mentions of Steel Boat Iron Hearts: A U-boat Crewman's Life Aboard U-505

I just finished reading Steel Boats, Iron Hearts by Hans Goebeler, who was a crewmember of the U-505, the U-boat that the US captured in WWII. In it he describes being able to hear the pings, but that they had to be very quiet to do so (of course, while being pursued they were very quiet anyway, to avoid detection).

That book was great by the way, I found it a very enjoyable read (although Hans isn't exactly an unbiased source, I have no idea how well regarded it is as a history rather than a memoir).