Getting dings instead of voice directions in Maps

The Maps app in Car play randomly starts giving ding sounds instead of voice directions. THIS IS DANGEROUS!!!! I need to take my eyes off the road to look at this screen when it beeps. I read the system converts to dings if the software needs an update. My phone software is up to date. The volume is up on the car and on my phone and Apple Watch. Why is Maps still not giving voice directions?