Playing heartbead sound, white noise or shushing, all familiar sounds from the womb, will help your baby to relax and drop off to sleep. A doctor-tested technique used by many sleep experts. Suzy has a choice of 6 different sounds and will shut off automatically after 20 mins. The unique cry sensor can automatically reactivate the sound whenever your baby starts crying. It's small, velcro strap and battery operation, make Suzy the perfect travel companion.