Age related changes in air and bone-conduction brainstem evoked response in children with normal hearing

Auditory Brainstem Response (ABR) test is the most common method of objective audiological test for hearing assessment of patients who are unable to cooperate pure tone audiometry testing. The implementation ABR through the air conduction provides information about the degree of hearing loss while application through bone conduction may provide additional information to determine the type of hearing loss. In order to measure sensitivity of hearing there are two options of sound delivery systems. Either bone or air stimulus delivery systems, wave V threshold estimation is used to measure hearing sensitivity. One of the important factors related to wave V latency is the age effect. To detect latency anomalies the prediction of the age effect on the wave V latencies has to be determined. Therefore, testing young children at various age groups with normal hearing are needed to establish the normative data. The purpose of this study is to establish age effect in ABR wave V latency and to establish age-related normative data. In our study, ABR test was performed on group of 51 children at various ages. Seventy six measurement were performed through the air conduction, while sixty five measurements were performed through bone conduction testing. Kolmogorov-Smirnov test was used to determine the data obtained from age groups providing a normal distribution or not. Independent non-parametric Mann-Whitney U test was used to compare wave V latencies of air and bone conduction systems between age groups. In all age groups, air and bone conduction wave V latency values in equivalent intensities were evaluated using non-parametric Speerman correlation test. In order to cross-check the results, not only cross-correlation but linear regression analysis was also performed. In this study, significant differences in air and bone conduction wave V latencies between the age of groups up to 12 month were found (p<0.05). However, no significant difference was observed after the age of 12 month. For clinical use, wave V latency averages obtained at intensities of 35 dB nHL, 25 dB nHL, 15 dB nHL through air and bone conduction normal values for over SS +2 were established.