When the Nav voice is speaking, the volume control indicator on the screen changes color, and the volume knob can be used to set the level FOR THAT VOICE alone - it does not change the volume of the media. Now, I can't say for sure that, even if you turn down the Nav voice to zero, that the computer won't turn down your media sound for the length of the sentence that the Nav voice is trying to say something even though you can no longer hear it ... but the point is that the Nav Voice actually has a separate volume setting that you adjust while she (usually she) is speaking.
In my current car (Merc 350E) I can only disable the voice per time that I start a new ride. I cannot disable it permanantely, curious of you can disable it permenantly in the Jaquar. Can anyone confirm?
This morning I found it, by accident. In the navigation screen, select the round icon with the 6 boxes, and on the lower right, is the button to mute ("dempen" in Dutch). Not sure if that is only for this ride, or if it is now of by default but I will learn soon enough.
Thanks stefxx - I have been trying to adjust the volume control when I think the navigation instructions should be given. It took several attempts to get the mute box to appear, but I can again go places without having to plug in my Android phone.