Transient evoked otoacoustic emissions: feasibility in the nursery

To assess the feasibility of obtaining transient-evoked otoacoustic emissions (TEOAEs) directly in the nursery, to examine the nature of failures in this population, and to determine the time requirements for this test relative to the auditory brain stem response (ABR).

TEOAEs and ABRs were recorded from 149 ears, at bedside, in the recovery or intensive care nursery. Subjects were selected according to the risk criteria developed by the Joint Committee on Infant Hearing (1991). Parametric and nonparametric statistical procedures were conducted to describe demographics and test results, to evaluate TEOAE measures by subgroups, and to compare infants by pass/fail outcome. Multivariate techniques were applied to the data to test implicit hypotheses regarding the source of TEOAE failures. In addition, the time required to carry out each test was evaluated in an analysis of variance design.

63.5% of the ears studied passed both procedures, 5% failed both, and 31.5% passed the ABR but failed the TEOAE. Although infants who failed the TEOAE had lower birthweights, shorter gestational periods, and were younger at the time of testing, no statistical differences were found for nursery (intensive care nursery/recovery), bed type (isolette/open crib), ear (left/right), or gender. Infants < 38 wk postconceptional age had smaller TEOAE responses and lower noise levels than did those > 37 wk. There were no differences in environmental noise levels (at the microphone) for passed or failed ears or whether infants were in isolettes or open cribs. Statistically prolonged ABR wave I latencies (Z-scores) at 60 and 30 dB among infants who passed the ABR but failed the TEOAE indicated some obstruction to the acoustic stimulus, whereas TEOAE noise measures neither distinguished these groups nor identified this condition. Three summary times involved in the performance of these tests were obtained: (a) actual test time, measured from start to completion of data collection with a stopwatch; (b) total test time, defined by the actual test time plus the respective preparation, setup, and cleanup (ABR) time; and (c) time reported by the computer system during intrinsic sampling. There were no significant differences in actual or total test times, but these values were distinguished from the machine time, which represented an underestimate of the time required to effectively conduct each test.

These findings show that TEOAEs can be acquired in the nursery, but the high false-positive rate suggests that alternative or additional screening methods, for example, the ABR, must also be available. It must be recognized that TEOAE failures increase test time, thereby negating any savings relative to ABR screening alone.