What are the relative merits of ABR and OAE for screening premature infants?
ABR can first be recorded at approximately 27 to 28 weeks conceptional age (Galambos & Hecox, 1978; Starr et al., 1977; Stockard and Westmoreland, 1981). The latency and amplitude is much more variable in premature infants than at term. In addition, the actual assignment of a gestational age by newborn medicine physicians is imprecise, with up to a two week margin of error. Infants in the neonatal and special care nurseries have a higher rate of transient effusion, which also creates problems for performing low level ABR. Lary et al. (1985) observed an ABR at click intensity levels in the range of 10 to 25 dB for infants with postconeceptional age of 40 weeks. In contrast, at a postconeptional age of 35 weeks, the average infant had an ABR threshold level of 30 dB. At 30 weeks, the average intensity level for ABR threshold was 40 dB. Unless you can tolerate a very high false positive rate in your screening program, screening at less than 35 weeks postconceptional age with a stimulus in
