Lexus 2013 GS 350 Owner's Manual page 449

The sound quality level is adjusted individually
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The treble, mid and bass levels can be adjusted for the each audio mode separately.
About Automatic Sound Levelizer (ASL)
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ASL automatically adjusts the volume and tone quality according to the vehicle
speed, wind noise or other noise.
GS350_U (OM30C34U)
5-3. Using the audio system
I n f o r ma t i o n P r o v i d e d b y :
5