Developers Two Tribes have announced on Twitter that Wii U allows separate audio to reach to both the TV and the Wii U GamePad. This is great news as this method worked really well on Wii especially for games such as Zelda: Twilight Princess and Super Mario Galaxy.
“ We’ve got the first audio code running on Wii U. You can send separate audio to game pad and TV. Not sure yet if and how we can use that.”