Toyota Lexusc Owner's Handbook Manual page 436

To adjust the volume of the headphones, turn the dial.
Left side dial: Turn it upward to increase the volume, turn it
downward to decrease the volume.
Right side dial: Turn it downward to increase the volume, turn
it upward to decrease the volume.
The maximum volume depends on the type of headphones.
With some headphone generally available in the market, it may
be difficult to catch sound properly. Lexus recommends the
use of Lexus genuine wireless headphone.
Please contact your Lexus dealer for further details.
CAUTION
Adjust the volume when you connect the headphones
to the jack. Loud sounds may have a significant impact
on the human body.
AUDIO
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