GOLF VII 2.0 TDI blue motion tech radio silence

Does anybody know how to auto-silent the radio when the navigator is providing driving indications?
The infotainement menu let Du choose if Du wish to auto-silent the navigator announcements during phone calls.
But I was not able to auto silent the radio when the navigator speaks. This can be very annoying because if Du set a high radio volume Du can't properly ear the navigator's indications. In any case if radio and Navigator speaks could be a confusing situation.
tks,
luciano