Soundly Sleeping helps your sleep by reducing the amount of external noise you will be subject to.
It produces continuous, uninterrupted random noise that effectively cancels out other sounds. All you have to do is pick between the exact randomness that suits your audio source best: white, pink, or brown. Essentially the sound gets lower from first to last - simply try out what works best for you. Set your volume - not too loud, we don't want to hurt your ears - and have a good night's sleep!