Effect of neonatal test environment on recording transient-evoked otoacoustic emissions

Objective. To examine the effect of test environment on recording transient-evoked otoacoustic emissions (TEOAE) in neonates. Methods. Thirty- two infants from the newborn nursery (NBN) who passed a screening auditory brainstem response (SABR) test and were at least 34 weeks' postconceptional age were studied. One ear of each newborn was tested using TEOAE in 5 different test environments: open bassinet in the NBN (E1), working isolet located in the NBN (E2), nonfunctioning isolet in the NBN (E3), nonfunctioning isolet in a quiet room off the NBN (E4), and open bassinet in a quiet room (E5). The number of high noise samples (HNS), the test duration (in seconds), the signal-to-noise ratio (SNR; in dB) measured at bandwidths centered at 1.6, 2.4, 3.2, and 4.0 kHz, and the percentage of neonates with a fail screening outcome based on a common pass-fail screening criteria were compared in the 5 test environments. Results. There were statistically significant differences in the number of HNS accumulated in the 5 test environments (F = 6.79). The use of a nonfunctioning isolet in both the NBN and within a room off the NBN (E3 and E4, respectively) resulted in significantly fewer HNS than when TEOAEs were recorded in the other 3 test environments (E1, E2, and ES). Mean test duration was significantly different among the 5 locations (F = 6.53). Posthoc analyses revealed that test time in E3 and E4 was significantly shorter than in E1 and E2. The percentage of newborns with a fail (≤dB SNR at 2.4, 3.2, and 4.0 kHz) outcome was lowest in E3 (6.3%) and the same in E1 and E4 (12.5%). A high percentage of infants received a fail outcome when tested in both the working isolet and in the open bassinet in a room off the nursery (21.8% and 25%, respectively). SNR (in dB) for bandwidths centered at 1.6, 2.4, and 3.2 kHz was negatively correlated with the HNS in the working isolet. SNR (in dB) at 4.0 kHz was negatively correlated with the HNS when TEOAEs were recorded in the open bassinet in a room adjacent to the NBN. The number of HNS was correlated with overall test time in each environment. Conclusions. Test environments typically used for newborn hearing screening can influence the recording of TEOAEs. Performing the TEOAE test with the neonate placed in a nonfunctioning isolet located in either the NBN or in a room off of the NBN resulted in the most desirable outcomes (shortest test times, fewest HNS, highest SNR (in dB), and fewest fail outcomes).