Re: No Voice Audio [PC]
As @holger1405 said, this sort of problem is usually the result of mis-configured speaker settings. Specifically, the device or game audio is configured to use a "Center Speaker" that doesn't exist. The music and background/sound effects play through the left/right channels just fine, but anything sent to the center channel isn't heard at all. And dialogue is usually set to play through the center speaker by default if the game thinks there is one.
(I first noticed this with my 5.1 surround rig when I plugged-in a headset while playing the version of "Solitaire" that shipped with WinXP. I would hear the deck being shuffled, but not the "ding" when placing a card on the pile!)