The effect of varying stimulus polarity (rarefaction Vs. condensation) on early auditory evoked potentials (EAEPs).

A patient with a vascular brain stem lesion was investigated with EAEP. The results suggest that rare-faction and condensation stimuli produce different responses. The alternating mode is a compromise and helps to suppress stimulus-related artifacts and cochlear microphonics. Wave form alterations and latency shifts must be recognized and taken into account in neurological applications of this test.