LG 47LM9600 Owner's Manual page 69

To set AV Sync
HOME Settings
Synchronizes unmatched video and audio. Select
audio output (TV speaker or SPDIF) with the video.
TV Speaker
SPDIF
SOUND
Adjusts the sync of the sound from the TV's internal speakers.
The "-" button makes the sound output faster and the "+"
button slower than the default value.
(Sony Philips Digital InterFace) Adjusts the sync of the sound
from speakers connected to digital audio out terminal.
The "-" button makes the sound output faster and the "+"
button slower than the default value.
AV Sync.
AV Sync. to On to synchronize