Wave IV and V of ABR are not always easily identifided, because of the compound formation of IV-V complex. To investigate modality of this IV-V complex of ABR, effect of masking noise on ABR (IV-V complex) was reported.
The results were as follows.
1) Masking noise level was insufficient to use for masking in ABR studies, in consideration with BI (Binaural Interaction).
2) The amplitude of wave IV, V and the peak of slow component decreased as the level of masking noise increased.
3) The ipsilateral recording of ABR was required to use masking of contralateral ear to eliminate shadow response. But there was some possibilities of the effect in the central lesion of auditory tract with masking noise.