Volvo 2006 S40 Manual page 104

Press MENU followed by ENTER.
Select AUDIO SETTINGS and press ENTER.
Select SUBWOOFER and press ENTER.
Surround sound
Surround settings are used to balance sound levels throughout the vehicle. Surround settings for FM and CD are stored
separately.
NOTE:
Dolby Surround Pro Logic II is only available on the Premium Sound system.
When listening to FM radio stations, Dolby Surround Pro Logic II functions best in areas with strong reception. If
reception is weak, selecting 2 or 3-channel stereo may provide better sound quality.
The Dolby symbol will be appear in the display when Dolby Pro Logic II is activated. There are three alternative
settings:
Pro Logic II
3-channel
Off (normal 2-channel stereo)
Activating/deactivating Surround sound
Press MENU followed by ENTER.
Select AUDIO SETTINGS in the menu and press ENTER.
Select Surround FM or Surround CD and press ENTER.
Select Pro logic II, 3-channel stereo or Off and press ENTER.
Equalizer Front/Rear
This function is used to fine-tune the sound from the front and rear speakers separately.
NOTE: This function is only available on certain sound systems.
To adjust the equalizer settings:
Press MENU followed by ENTER.
Select AUDIO SETTINGS in the menu and press ENTER.
Select Equalizer Front/Rear and press ENTER.
The column in the display indicates the level for the current frequency.
Adjust the level with the Tuning dial (4), or use the Up/Down arrows. Additional frequencies can be selected with
the Right/Left arrows.
Save the settings by pressing ENTER or exit without saving by pressing EXIT.
ASC - speed compensated volume
The audio system's volume is adjusted automatically according to the speed of the vehicle. There are three settings
available, which determine the level of volume compensation:
Low
Medium*
High