Lexus rx450h 2015 Owner's Manual page 425

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 Leveliser (ASL)
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ASL automatically adjusts the volume and tone quality according to the vehicle
speed.
3-3. Using the Lexus Display Audio system
I n f o r ma t i o n P r o v i d e d b y :
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