The short-gestation infant is at risk for both mortality and morbidity. His writhing contributes to weight loss; his extrauterine environment does not contain the multimodality patterned afferent stimuli that excite the developing brain in utero. Sound is the most effective modality to achieve concurrent decrement in motility along with enhancement of cortical activity. It was anticipated that by 36 gestational weeks, subjects exposed to 5 min. of patterned sound 6 times a day would (a) evidence less gross motor activity and (b) evidence a greater decrease in motor actitvity with a maternal auditory stimulus than with a musical auditory stimulus. The sample consisted of 80 males and 73 females whose gestational age at birth was 26 to 33 weeks. Fifty-two subjects were randomly assigned to the control group, 50 to a tape of their mother's voice, and 51 to a lullaby. Limb activity was measured just before discharge by accelerometers worn unilaterally for a 24-hr. period on the ankle and wrist prior to transfer to the alternate side for a further 24 hr. No statistically significant differences were demonstrated among the three groups' limb patterns. Large intragroup variation in gross activity precluded demonstration of between-group differences. The majority of subjects evidenced predominance of upper limb activity and laterality.