[The effect of rarefaction and condensation tone pips on early auditory evoked potentials (EAEP) (author's transl)]

Tone pips of suprathreshold intensity were used to elicit 7 potentials in the nanovolt range. The acoustic nerve response (I) and 4 brainstem potentials (II-V) were studied in 8 normal listeners in regard to varying acoustic polarity (rarefaction vs condensation). Rarefaction and condensation stimuli produced different responses. In the alternating mode, which helps to suppress stimulus related artifacts, waves may be generated solely as a function of the averaging process if the responses of the two types of tone pips are almost out of phase. Rarefaction tone pips exhibited a better synchronizing effect on auditory unites in the periphery and in brainstem areas. The different responses evoked by stimuli of different polarity must be recognized and controlled in neurologic application of the test.