Evoked otoacoustic emissions in preterm infants.

Since Kemp's discovery of the otoacoustic emissions phenomenon [7], much study has been given to understanding the nature of it and its ontogeny. Development of the evoked otoacoustic emissions (EOAE) has spurred much interest because they may used as a valid and relatively quick test to assess cochlear integrity in the very youngest patients. One thing that has been learned is that EOAE amplitudes are much larger in normal ears of infants than in normal ears of adults. We asked about the form of this development in a longitudinal, rather than cross-sectional, study in an investigation on children born before 40 weeks postconceptional age. We were able to examine reliably five ears of four preterm babies while they remained in the neonatal intensive care unit. The EOAEs of these ears were then studied to determine whether and how they changed over time. To do this, we examined both their amplitudes and their spectral properties. It turned out that there are properties of the EOAE spectrum that may be related to post-conceptional age. These are described herein. These findings are expected to have considerable clinical utility as more and more researchers are able to confirm their validity.