the sound should come out of the computer sound card speaker connection. Your video card has DVI output and DVI don't have sound as hdmi have.
We have an LG37LC2D-UD (June 2006 model) that we are attempting to connect to a Dell Studios XPS with and Intel (R) Core (TM): 7 CPU running Windows 7 Enterprise (6 GB RAM, 64 bit os). We tried to connect the high speed HDMI cable through the NVidia GE Force 310 sound card on the desktop cpu. We have great video but no sound. We are stumped. Any help would be most appreciated.