From the Voice Coach settings page (Menu > Settings > Voice Coach), scroll to the bottom and turn up the Master Volume and the Relative Voice Volume. The Relative Voice Volume adjusts the volume of the voice updates relative to your iPod music.
From the Voice Coach settings page (Menu > Settings > Voice Coach), scroll to the bottom and turn up the Master Volume and the Relative Voice Volume. The Relative Voice Volume adjusts the volume of the voice updates relative to your iPod music.