Digital sound processor
WARNING: This page is about a different car, the 2013 BMW X5, 2012 BMW X5, and 2011 BMW X5. However, it is still accessible from the selected car via links, so may be relevant.
The digital audio signal is then processed by the DSP and converted. The volume of the different frequencies in the audio signal is individually adjusted to suit the particular vehicle. This generates an optimal sound pattern.