May 03, 2013, 2:47 PM — Here's how you can adjust the volume of the turn-by-turn directions in iOS Maps. This will let you hear iOS Maps at a different volume than your main volume settings.
1. Go to Settings.
2. Go to Maps.
3. Tap on your preferred voice navigation volume, you can choose from the following options:
For more, see the original article at the link below.