To put your vocal likeness in control of the directions, you'll first have to open the app settings, tap on "Sound and Voice" then select the option to record a new voice. You'll have to record a bunch of generic phrases first like numbers, "Turn Left" and "In 100 feet" first but after that, you're free to customize the instructions as you see fit. While the potential uses for localization (and pranks) is nearly limitless, the feature is currently can't be shared. So if you want to show off your fancy navigation voice, you're going to need to go for a drive.