Hearing threshold investigations in infants and children

The influence of age on the auditory brainstem responses (ABRs) of 39 normal infants (aged less than 6-18 months) and children (aged 19 months to 3.5 years) was investigated. While the ABR threshold of infants (mean value: 9.3 dB nHL) is still slightly higher than that of normal-hearing adults, children show a distribution which corresponds approximately to that of adults. The mean I-V interpeak interval of the ABRs of these children is slightly longer (4.1 ms) compared with a normal value in the range of 3.95 ms. Furthermore, a comparison was made between the threshold values measured by brainstem-evoked response audiometry and conditioned orientation reflex audiometry in 115 children of between 6 months and 3.5 years of age who were suspected to be hearing impaired. In the case of normally configurated ABRs there was an 86% agreement of thresholds (within the limits of +/- 10 dB) while it amounted to 66% in the case of ABR changes, which indicates brainstem lesions.