let me guess, you have your phone plugged into the usb port cable when you have no voice on google?
If that is the case, switch your stereo to blutooth instead of CD, radio, etc.
Another solution if you want to listen to the radio at the same time is to NOT use the USB port, and use an 12v adapter to usb. You will then hear the google voice via blutooth as it should interrupt your radio, although it is not plugged into a data connection, so you don't have to be on blutooth audio on your car the whole time.