Identification of neonatal hearing impairment: Hearing status at 8 to 12 months corrected age using a visual reinforcement audiometry protocol

Objectives: 1) To describe the hearing status of the at-risk infants in the National Institutes of Health-Identification of Neonatal Hearing Impairmen t study sample at 8 to 12 mo corrected age (chronologic age adjusted for pr ematurity). 2) To describe the visual reinforcement audiometry (VRA) protoc ol that was used to obtain monaural behavioral data for the sample. Design: All neonatal intensive care unit infants and well babies with risk factors (including well babies who failed neonatal tests) were targeted for follow-up behavioral evaluation once they had reached 8 mo corrected age. Three thousand one hundred and thirty-four (64.4%) of the 4868 surviving in fants returned for at least one behavioral hearing evaluation, which employ ed a well-defined VRA protocol. VRA thresholds or minimum response levels ( MRLs) were determined for speech and pure tones of 1.0, 2.0, and 4.0 kHz fo r each ear using insert earphones. Results: More than 95% of the infants were reliably tested with the VRA pro tocol; 90% provided complete tests (four MRLs for both ears). Ninety-four p ercent of the at-risk infants were found to have normal hearing sensitivity (MRLs of 20 dB HL) at 1.0, 2.0, and 4.0 kHz in both ears. Of the infants, 2.2% had bilateral hearing impairment, and 3.4% had impairment in one ear o nly. More than 80% of the impaired ears had losses of mild-to-moderate degr ee. Conclusions: This may be the largest study to attempt to follow all at-risk infants with behavioral audiometric testing, regardless of screening outco me, in an effort to validate the results of auditory brain stem response, d istortion product otoacoustic emission, and transient evoked otoacoustic em ission testing in the newborn period. It is one of only a few studies to re port hearing status of infants at 1 yr of age, using VRA on a clinical popu lation. Successful testing of more than 95% of the infants who returned for the VRA follow-up documents the feasibility of obtaining monaural behavior al data in this population.