Breathing cessation happens frequently among infants in neonatal intensive care units, particularly among premature infants. Most instances are benign respiratory pauses; however, some are significant apneic spells--breathing pauses longer than 20 sec or associated with bradycardia or cyanosis. These apneic spells must be recognized promptly and the infants stimulated to breathe to avoid brain damage or death from hypoxia. Apnea monitors now in use can detect some types of apneic spells, but not those in which airflow has been occluded but breathing motions continued. Monitors that measure air flow have been developed, but are not yet perfected for clinical use. An acoustic air-flow monitor has been developed that registers apneic spells more reliably than monitors now in use, and does not affect the infant's normal breathing.