Toyota C-HR Owner's Manual page 309

308
5-2. Using the audio system
Adjusting the Automatic Sound Levelizer (ASL)
■
When ASL is selected, turn the tune/select knob to change the
amount of ASL.
"LOW", "MID", "HIGH", or "OFF" can be selected.
ASL automatically adjusts the volume and tone quality according to
vehicle speed.
Press the knob or
menu.
C-HR_HV_OM_General_OM10653E
("BACK") to return to the sound setting