Audio Unit (Built in the navigation unit)
WARNING: This page is about a different car, the 2008 Acura CSX, 2007 Acura CSX, and 2006 Acura CSX. However, it is still accessible from the selected car via links, so may be relevant.
The audio unit receives the audio driving instructions from the navigation unit, and transmits the instructions through the front speakers even when the audio system is in use.