This app is simply fantastic. I use it with my iPhone in a charging stand (so I can see the screen) and a Bose Mini SoundLink, both sitting on my nightstand. It offers multiple "themes" (Beach, River, Forest, Waterfall, etc.) each having a baseline sound. Then you can add in additional sounds (birds, chimes, rain, crickets, etc.) and modify the volume of each sound to create your own personal custom symphony. The phone screen displays a start/pause button together with the time and date, superimposed on a peaceful scene representing the particular theme thats currently playing. Its really very slick!
The "free" version comes with a generous 12 themes—more than enough for most peoples needs. However, I suggest you consider purchasing the "Pro" version (for a whopping $1.99!) as I did, simply to show your appreciation to the developers for giving us such a wonderful app. (The Pro version provides another dozen themes.)