Volvo C30 Owner's Manual page 256

10 Infotainment system
Audio functions
There is a also a dynamic calibration that takes
into account the position of the volume control,
10
radio reception and vehicle speed.
The controls explained in these operating
instructions, e.g. bass, treble and equalizer*
are only intended for the user to be able to
adapt the sound reproduction according to
personal taste.
*
256
Option/accessory, for more information, see Introduction.