Sony VGC-RB64GY - Manual (Page 111)

Why can't I hear dialogue during DVD movie playback, using my 5.1 channel 1 speaker system?
 Verify that your speaker system is connected correctly.
 Change the computer's audio settings to 6-channel, to match your 5.1 speaker system.
 Change the audio settings in the RealTek ® Sound Effect Manager software program.
 Change the audio settings in the InterVideo ® WinDVD ® software program.
 Change the audio settings in the Media Center software program's DVD settings.
1 Your computer's supplied accessories may not include a 5.1 channel speaker system. See your specifications sheet for
details on your computer's supplied accessories.
Page 111