LG 42PM4700 Owner's Manual page 85

Bypass
To use ARC mode
❐
HOME ➾ Settings
External audio devices that support Audio Return Channel (ARC) can be
connected with High-Speed HDMIⓇ cable without an extra optical audio cable to
output SPDIF. It interfaces with SIMPLINK.
For an external device that supports ARC (Audio Return Channel), connect it to
the HDMI(ARC)
Outputs broadcasting signals or the audio of an external
device without audio delay. Audio may be output before video
as it takes time to process video input into the TV.
➙ SOUND
port.
➙ Sound Setting ➙ ARC Mode