The influence of stimulus intensity, contralateral masking and handedness on the temporal N1 and the T complex components of the auditory N1 wave

Components of the auditory N1 wave were recorded to confirm previous findings of contralateral dominance of the negative component (Tb) of the T complex and to examine the differential sensitivity of N1 components to stimulus intensity, contralateral masking and handedness. EEG was recorded from Cz, T3, T4, T5, T6, and at points midway between C3 and T3 and C4 and T4 using a non-cephalic (S-V) reference. Stimuli of 70 and 90 dB SL were presented monaurally with and without contralateral white noise masking. The N100 component generally occurred at all sites and at temporal sites tended to be larger ipsilateral to stimulation and occurred earlier at ipsilateral compared to contralateral sites. Tb was seen at temporal sites and proved to be larger and earlier contralaterally. The positive component (Ta) of the T complex tended to be larger ipsilaterally although its latencies, like Tb, were earlier contralaterally. Although ERP differences associated with handedness were observed they were unrelated to ipsilateral/contralateral auditory pathway patterns. Results are discussed in terms of the functional independence of negativities recorded at temporal sites and the differential utility of these negativities in the examination of auditory pathway function.