Hi
I have TomTom One. I downloaded the voice warning file from http://tomtom.gps-data-team.com/tomtom_voices.php and copied the voice files into the map folder (Folder name: Australia) of TomTom One. The file names in the folder look like below;
Hi
OGG is tomtom's undocumented feature and is not supported by all TomTom models. However, you can create your own voice file or use any available free voices for TomTom: http://tomtom.gps-data-team.com/tomtom_voices.php