It's about the speaking itself. I have a hard time with auditory discrimination so I have difficulty speaking if others are as well because I can't properly listen to myself speak.

I wish there was a level of detail slider for the navigation system, because by default I think it's overly detailed and verbose in many instances. An option to skip the first n instructions or any instructions within an x mile radius of my home would be nice too. I don't need the navigation to tell me how to get to the major highways near my home, just which one to go to.