Sat Nav turn off street name voice announcements?

Hey, is there a way to turn off spoken street name directions, such as "turn left into 'can alley',
I have the English voice set and live in Germany, the spoken street names are a disaster and an embarrassment.
I live in hope, I have searched through the manuals and not found anything, just need to know turn left or right, in any case who has time to look at street names for gods sake.

I suspect sound is either off or on!
I have a Mercedes e class as well, and the satnav only does 4 digits, which is much more useless.