You can adjust the volumes for the narration and scenes independently by doing the following:
When a session starts, tap the screen and an icon will appear at the bottom of the window, below the volume slider. Tap that icon, and a sound mixer will appear. Move that slider to the left to decrease the background sound volume relative to the narration, or slide it to the right to increase the background sounds.
If you do not wish to have any background sounds during your session, we recommend using the 'Silent Clouds' or 'Planet Earth' background, as these are both silent.