but the Germans were a bit further along than you say with acoustic torpedoes. You described Falke and to some extent Zaunkoenig I, but Zaunkoenig II had a primitive analog signal processing system which would have outfoxed the "Foxer". Further, there was Lerche which was similar to Zaunkoenig II, but was wire guided so the sonarman could hear the target via the wire. This would have been a very reliable weapon if it had appeared earlier. Both Lerche and Zaunkoenig II were available in small numbers at the end of the war. The priority placed on these advanced torpedo programs was quite low and many projects were in stop and go mode.

It should also be pointed out that the British knew all about the basic German acoustic torpedo technology through a package of documents which was tossed over the wall of the British embassy in Oslo early in 1940, the so called "Oslo Report". The information contained in this report allowed the development of the noisemaker called Foxer. It also allowed the British to negate the various radionavigation beams the Luftwaffe used during the night bombing phase of the BoB and there were other tidbits there as well.

Regards,
SuperKraut