FREQUENCY SPECIFICITY OF EARLY AND MIDDLE LATENCY AUDITORY-EVOKED POTENTIALS INVESTIGATED BY HIGH-PASS NOISE MASKING

In contrast to auditory brainstem potentials (ABR),a more apically def ined generation of middle latency evoked potentials (MLR) can be assum ed due to the longer integration time present.To date, the effect of s timulus frequency spectra on MIR has not been completely known. By usi ng masking with high-pass filtered white noise in 12 normal-hearing ad ults, we measured the dependence of amplitude and latency of ABR and M IR on filter frequency. No differences were found between the masking effects for ABR and MIR evoked by tone bursts of 0.5 and 2 kHz. The hi gh-pass masking of click stimuli showed a greater influence on the amp litude and latency of the ABR than on MLR. These different qualities h ave to be considered clinically when evaluating the methods and result s of hearing testing with acoustic evoked potentials. Our findings sho w that MLR evoked by tone bursts should be used for the frequency sele ctive diagnosis of hearing thresholds, especially in low-frequency ran ges.