Annoying thing:
 

I use the very good Mod wassabomb or SON-deth-charge.
Good - but there are inconsistencies in the sound management of the original game:
For example, you can hear airplane engines from inside the sub; also at periscopic depth the Vzzz of tracer bullets ....
If a little genius could rectify all this, in the file "Sh.sdl" I presume ?