I was specifically looking for this type of feature as an in-app feature, where you could add a playlist or an audiobook to the app’s audio stream and mix in relaxation sounds and the binaural beats. I found apps that would let you add a song, but not a playlist or an audiobook.
While demoing the free version, I decided to try launching the Music app after I started the relaxation session, and was surprised to find it mixed the two audio streams together. Perfect.
The relaxation sounds are pretty good as well, not too New Age-y, unobtrusive, and I really like the feature where it will auto-mix all the loops in each category. The blending works great.
I’ve only just begin to play with the app and picked up the Pro version which is currently on sale for 99¢.