Phase I: 15 preterm infants on Bubble Continuous Positive Airway Pressure (bCPAP)

Group 1 will consist of 15 preterm infants on bCPAP in whom the external bubble CPAP sounds and the pressures from the CPAP system itself will be recorded for 3 hours. To do so, we will use a standard microphone placed on the water tank and an external pressure transducer inserted into the expiratory limb of the bubble CPAP circuit.

Phase II: 15 preterm infants on Bubble Continuous Positive Airway Pressure (bCPAP)

Group 2 will consist of 15 preterm infants on bCPAP in whom the external bubble CPAP sounds and the pressures from the CPAP system itself will be recorded. To do so, we will use a standard microphone placed on the water tank and a pressure transducer inserted into the expiratory limb of the bubble CPAP circuit. In addition, the internal bubble CPAP sound and pressure transmitted to the infant's lungs will be measured. For these, a wireless acoustic sensor will be secured on the infant's suprasternal notch to capture transmitted CPAP sounds, and an internal pressure transducer will be inserted from the infant's mouth into the nasopharynx to record the pressure delivered in the airway. Data will be recorded for 3 hours.