Premature infants in the neonatal intensive-care unit often are exposed to continuous loud noise. This excess auditory stimulation creates negative physiological responses, such as increased heart and respiratory rates and decreased oxygen saturation. Modifying the neonatal intensive-care unit to reduce noise levels provides an environment more conducive to maturation and recovery from illness. This article reviews the literature addressing the pathophysiology and physiological changes of the premature infant in response to stress and discusses practice interventions for decreasing noise levels in the neonatal intensive-care unit. These interventions include installing sound absorbing materials and minimizing conversations of the staff.