If you have the file but still can't hear voices, ensure your Windows sound settings are set to Stereo rather than 5.1 Surround, as the game often fails to route dialogue to the center channel correctly on older PC ports.
This specific file, sounds-eng.pck , is the for Assassin's Creed II sounds-eng.pck assassin 39-s creed 2
file, a proprietary data container located within the game's SoundData/pc If you have the file but still can't