If binaural beats and white noise were added this would be the only app. one would need. Each of them could be used in combination or separately. The best examples of binaural apps. are Binaural Beat Builder and Brainwave Studio. White Noise has a selection of different sounds. This would be the grand app. for breathing, meditation, sleep and lucid dreaming. As it is, I use three different apps. at the same time.
Kardia+ Deep Breathing Relaxation at Google Play market analyse