SCV
The audio system has a feature called Speed Compensated Volume (SCV). With SCV, the audio system adjusts automatically to make up for road and wind noise. Set the volume at the desired level. Turn the control ring behind the upper knob clockwise to adjust the SCV. SCV automatically increases the volume, as necessary, to overcome noise at any particular speed. The volume level should always sound the same as the vehicle is driven. If SCV is not wanted, rotate the control all the way down. Each notch on the control ring allows for more volume compensation at faster vehicle speeds.