Contralateral White Noise Masking Affects Auditory N1 and P2 Waves Differently

Abstract

Abstract In this study, we examined the effect of contralateral masking on cortical auditory evoked potentials N1 (modal-specific slowly adapting component) and P2 at different masking intensities. N1 and P2 potentials were recorded from 15 subjects with normal hearing using 500Hz tone pips (intensity 65dB HL, duration 100ms, ISI 1s) presented to the right ear. Continuous white noise was delivered to the left ear at the intensities of 35, 50, 65, or 75dB effective masking level (EML), as well as a no-mask condition. The electrodes F3, Fz, F4, C3, Cz, C4, and Pz were used. The results show that N1 amplitude was significantly attenuated and, in contrast, P2 amplitude was significantly increased, with contralateral 75dB EML white noise. N1P2 peak to peak amplitude was not affected by masking, nor were the peak latencies. Thus, contralateral masking affects the exogenous cortical evoked N1 and P2 curves differently. We suggest that the effect is mediated by the efferent hearing system. The effect of ≤ 50dB EML contralateral white noise masking is so small that it should not affect clinical recordings.