Combined effect of click rate and stimulus polarity on BAEP latencies.

Previous studies addressed themselves to the effect of different parameters on the brainstem auditory evoked potentials (BAEPs). Of special interest were the repetition rate and the click polarity, both able to influence significantly the results. While previous contributions studied these two parameters separately, the present investigation is concerned with their combined effect, non-parametric statistical analyses allowing simultaneous consideration. 37 patients, 21 females and 16 males, with an age range of 20 to 95, carrying different diagnoses, were studied using rarefaction as well as condensation polarities, 10/sec as well as 30/sec repetition rates. Abnormalities present with only one stimulus polarity and repetition rate but not with another combination were present in 24 cases for polarity dependent changes (64.9%) and in 25 (67.4%) cases for repetition rate dependent ones. Generally 30/sec repetition rate yielded longer latencies when repetition rates were kept constant. The combination of condensation clicks and high repetition rates revealed a strong correlation with higher latencies.