http://www.navitotal.com/showthread.php?4173-TomTom-silent-voice

"The silent voice is especially good, if you have setup Speed camera warning alerts"

This does not work on my go 930. silent voice means silence. no speed camera alerts when silent voice is turned on.

what could it be?

The voice has nothing to do with the warnings.
It is a silent voice - that means instead of an instruction you will get nothing, just silence.
Cam warnings are assigned either using the speed cam preferences (original TT cams), or by assigning a warning tone to the POI (third party cams).

comeon wrote:This does not work on my go 930. silent voice means silence. no speed camera alerts when silent voice is turned on.

Confirm that you understand that this is a file that you download, put in your voices folder, then select with Main Menu, Change Preferences, Voices, Change voice.