[Visual scoring in the auditory brainstem response. Second report: determination of response threshold].

In the ABR audiometry we usually determine the threshold by visual scoring. The evaluation of visual scoring has been investigated in my laboratory for several years, using the traced samples of ABR obtained from 3 normal adults same as that described in my previous report. Stimuli were clicks of 0, 5, 10, 15, 20, 30dBSL and without stimulus. Thresholds were calculated by the two psychophysical methods, "method of limits" and "up and down method". Scorers were two groups: 3 experienced and 3 inexperienced. Results obtained were as follows: 1. In the method of limits, averages of thresholds measured by the experienced scorers were contained 6.0-9.8dB, their standard deviations being 3.82-6.40dB. 84-95% of all thresholds were contained 0-10dB or 5-10dB in the experienced group. 2. In the method of limits, the highest rate that all scorers of a group had the same threshold was 56% in the separate presentation in the experienced group. 3. In the up and down method averages of threshold were contained 4.6-9.1dB, which were smaller than the method of limits, and standard deviations were contained 1.77-3.18dB, which were about 1/2 times in the method of limits. 92-99% of all thresholds were contained 0-5dB or 5-10dB.