Babies are born with fluid in their middle ear (behind the eardrum), so their hearing is not as sensitive as it will be in about 2 weeks when this fluid is absorbed. Nevertheless, they can tell the difference between loud and soft sounds and between short and long sound duration. The auditory feedback loop is already present and used by your newborn baby. The auditory feedback loop is the relationship between the ability of a baby to use sounds that she hears in order to control or monitor sounds that she produces. Experiments testing the auditory feedback loop examine a baby’s change in heart rate or breathing rate in response to presentation of the same or a different sound. Amazingly, within the first few days after birth, babies can tell the difference between sounds. Distinguishing specific sounds in words, however, comes later. But newborns are able to perceive a great deal right from birth.