Abstract
Excessive sound levels of preterm infants may contribute to negative physiological effects. Yet, recommended sound level limits are consistently exceeded at neonatal intensive care units (NICU), both inside and outside of the incubator. We present the results of a measurement campaign at two Norwegian hospitals with different design of the NICU. The first hospital had a shared unit with several incubators in one room while the second one featured single patient room. Sound pressure levels were measured continuously for several days inside of an unoccupied incubator and outside several active incubators. Additionally, sound pressure levels of an incubator were measured in a quiet room for several operation modes. The sound levels at both hospitals exceeded the recommended limit values. Although the incubator provides considerable attenuation of the environmental sound, the sound level inside the incubator was dominated by the contribution of the machine itself and exceeded the recommended limit values considerably. We conclude that the design of the NICU has some effect on the sound levels inside the incubator. However, without reducing the sound levels from the incubator itself, such measures have a minor effect on the infant exposure to excessive sound levels.