Panasonic TC-55CX400U Owner's Manual page 22

Press buttons to select SOUND menu and then press OK button to enter. Use
the following sound options and then use
Sound Mode
Bass
Treble
Balance
Digital Out
Surround Sound
Auto Volume
Audio Language
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buttons to set each option's setting.
Allow the selection of an audio-enhancement technique: Standard/
Music/Cinema/Custom.
Alternative: you may press the S.MODE button to select the sound
mode directly.
Control the relative intensity of lower-pitched sounds.
Control the relative intensity of higher-pitched sounds.
Adjust the relative volume of the speaker in a multiple speaker
system.
Select the digital audio output mode between RAW/PCM.
Select surround sound between Virtual or Off.
Volume levels are automatically controlled by turning On/Off.
Select audio language among: Main/1/2.
SOUND
buttons to select