Maternal Whispers is the only baby sleep CD that actually mimics what a baby hears in the womb. Other CDs claim to use “rhythmic womb sounds”. But they are actually recordings of an ultrasound machine in a doctor’s office – hardly something familiar-sounding to a baby! You can verify this by listening to the heart beats on a typical baby sleep CD: the rhythm you will hear is a baby’s heartbeat, NOT a mother’s … and this makes a big difference! The pulse and blood flow of the mother (the sounds the baby is most used to hearing) remain perfectly steady throughout, for 72 minutes, giving your baby a rhythmic and familiar sound to sleep to.