You can play the sounds while you sleep or take a nap. They will continue playing while your device is sleeping or locked. Includes the following 21 sounds: Dusk in the Country Night Ambience 1 (with crickets and frogs) Night Ambience 2 (with crickets and frogs) Gentle Ocean Waves Cascading Waterfall Thunderstorm 1 Thunderstorm 2 Heavy Raining Mystical Ice Country Stream (new) Wind Chimes 1 (new) Wind Chimes 2 (new) Brown Noise (new - excellent noise-cancelling sound) Pink Noise (new) Grey Noise (new) White Noise (new) Shower Sounds (new) Vacuum Cleaner Sounds (new) Fan Sounds 1 (new) Fan Sounds 2 (new) Fan Sounds 3 (new)