Open the main menu and select Settings > Navigation > Voice navigation.
Standard male and female navigation voices are available to download. All of the navigation voices are standard-quality but don't announce street names. They will, however, tell you which way to turn and when.
If you download a map of a country or region and use drive navigation there, you won't automatically hear voice navigation in a language spoken in that country or region. Navigation voices and downloaded maps behave independently of each other.