Will contralateral white noise interfere with the monaurally click-evoked brainstem response?

Monaurally evoked (and ipsilaterally recorded) ABRs to clicks at 70 dB nHL in the presence of contralateral masking by white noise at 60, 70, 80 and 90 dB HL were compared with the corresponding ABRs without contralateral masking. The investigation was performed in 11 normal, young female subjects. There were no differences concerning wave shape and relative amplitudes, except slight changes in one subject. The following latency findings concern group statistics. The latency of wave I did not change significantly with contralateral noise at any one of the four levels. The latency of wave III was significantly prolonged only at the noise level of 90 dB HL. The latency of wave V was significantly increased at the noise levels of 80 and 90 dB HL. The average latency prolongations were on the order of 0.05 ms. The findings suggest the latency increments to be attributable to central masking rather than to acoustic crossover or stapedius reflex elicitation. Contralateral white noise levels below 80 dB HL would not seem to affect the ABR to clicks above 65 dB nHL.