Noizio - Feeling that the noise of the big city is too much for you to bear?
Rootd - Anxiety and panic attack relief for iOS & Android
A Soft Murmur - Ambient sounds to wash away distraction.
Calm - Calm.com can help you reduce stress and increase calm.
Defonic - Create a unique sound environment at home or in the office
Headspace - Meditation made simple. Brilliant things happen in calm minds.