Distortion-product and click-evoked otoacoustic emissions of preterm and full-term infants.

Full-term and preterm infants were evaluated with click-evoked and distortion-product otoacoustic emissions (CEOEs and DPOEs). The CEOEs and DPOEs recorded from each individual ear were analyzed by calculating the root-mean-square levels within half-octave bands. The fail criterion of the OE tests was that the half-octave RMS DPOE or CEOE levels of an ear under test were below the 10th percentile of full-term newborns in two or more bands. The DPOE data were collected from 118 ears of 61 premature babies; 80 (68%) ears passed the DPOE test, 30 (25%) ears without middle ear effusions failed the test, and 8 (7%) ears with effusions also failed. The CEOE data were collected from 128 ears of 65 premature babies; 102 (80%) ears passed the CEOE test, 18 (14%) ears without middle ear effusions failed the test, and 8 (6%) ears with effusions also failed. In 23 of 80 ears (29%) that passed the DPOE test and in 23 of 102 ears (23%) that passed the CEOE test, RMS OE levels of preterm infants were above the 90th percentile of full-term newborns. The analyses of the combined DPOE and CEOE data obtained from a group of 25 ears of full-term newborns and from a group of 72 ears of preterm babies showed statistically significant correlations between the DPOE and CEOE root-mean-square levels in each of the half-octave bands in the 1.4 to 4 kHz region. For 42 preterm infants tested with auditory brain stem response (ABR), specificity was 86% for CEOE and 74% for DPOE. All infants who failed the ABR also failed OE tests. To the best of our knowledge, this study is the first using combined DPOEs, CEOEs, and ABRs for preterm babies. It showed the feasibility of DPOEs and CEOEs for this population.