Well I managed to make the following sounds (which didn't work with "Spax's patch" )work in German:
Torpedo in the water
Torpedo Impact
Torpedo is a dud
Torpedo Missed Sir
Firing Tube 1.....to Tube 6.
I suspect that more sounds will be revealed to be in English but those are very common..
Just enable this little mod on top of "Spax's" and it should work.
http://files.filefront.com/Speech+Fi.../fileinfo.html
If you don't want to take any chances that in the middle of a battle you will hear an out of place English voice you should delete ".../Silent Hunter 4/Data/Sound/Speech" folder (backup first) and then install those two mods. Off course if a sound was in English, this way you should not hear it at all.