Came across this WRC 7 Guide in Steam> Hate the "Brake!" or some other callouts? You can delete them from gamefiles>
http://steamcommunity.com/sharedfiles/filedetails/?id=1187924134
Deleting callout audio files, Braking calls will be heard, even if you set "Co-driver detail" to minimum.
I found them distracting, because in many places you shouldn't really brake much at all if you want fast time. They don't also care about your speed, so if you go 2 km/h it will still tell you to "Hard brake!"
If you installed the game on for example C: drive, go to folder:
C:/Program Files(x86)/Steam/steamapps/common/WRC7/WIN32/Sounds/Voice/EN/PACENOTES
Here are the audio files. Delete any you dislike. I deleted the "Brake!" and "Hard brake!" callouts, but you can delete for example all "Short" callouts, to make pacenotes less cluttered.
Obviously if you don't use English audio, go to your respective language folder instead of /EN
To search for all callouts you can use Ctrl+F function of Windows Explorer with search word "brak" or "short" etc. and just delete all of it. Game will start no problem, and these audio files won't be heard.
If you deleted wrong files or want to go back, you can do Steam integrity check, to redownload files, without downloading entire game.
What l did was to create a folder In Pacenotes called it Pnotes> but l use CUT instead of DELETE and put them in the folder l created.
So all you have to do is replace them back far easier if you make a mistake.