The introduction of turn-by-turn voice guidance to the Apple Maps app in iOS 6 was a welcome addition, but if you regularly listen to music or other audio from your iPhone while driving you may find the volume of the spoken directions doesn’t always match up well.
Fortunately, Apple provided a way to adjust this separately from your main device volume—simply go into your Settings app and select Maps and you’ll find four options under “Navigation Voice Volume” to adjust between three different presets, or turn the voice off entirely if you’d rather just rely on the visual directions.
.