6 Nature Sounds: Waterfall; Rain forest; Spring rain; Summer night; Ocean; Heartbeat (Simulates Mother's natural heartbeat). Rest anywhere with soothing natural sounds. Create a perfect sleep environment. Sound Spa filters out background noise as you read, work, study or rest. At night it helps you fall asleep faster and wake completely rested. 6 Digitally recorded natural sounds. Timer to turn off after 15, 30 or 60 minutes. Compact & lightweight for travel. Use adaptor or batteries (4 AA Batteries not included). Create a comforting environment for infants & toddlers. Babies are comforted by rhythmic, repetitive sounds, the sound of the human heartbeat can be considered nature's most soothing sound. This product employs a UL listed adaptor.