Let there be sound.
http://www.nintendoworldreport.com/news/37340/giana-sisters-twisted-dreams-patched
The European version of Giana Sisters: Twisted Dreams has been patched to add sound to the game's off-TV play.
Black Forest Games stated that the patch was also submitted the to Nintendo of America at the same time, but is unfortunately still in QA.
Hi Europe, are you playing Giana on the WiiU-pad and missed some sound so far? Try it out now, Nintendo released the patch!
— Black Forest Games (@BlackForestTeam) April 30, 2014