The purpose of this RCT is to learn more about how sounds that we experience in the womb can affect early development in premature infants. The investigators are specifically interested determining whether and what types of maternal sensory stimulation can influence physical growth, brain maturation, respiratory stability and early vocalization during postnatal development. The investigators hypothesize that daily exposure to biological maternal sounds, such as mother's voice and heartbeat, will improve both short-term and long-term developmental in premature infants and will increase their potential to grow into healthy children.