Evoked potentials: computer-automated threshold-tracking procedure using an objective detection criterion.

A computer-automated, threshold-tracking procedure was developed for measuring evoked response thresholds on-line. The procedure utilizes an objective detection criterion (correlation) to evaluate whether a response is absent or present. Sound intensity is adjusted according to a modified PEST (parameter estimation by sequential testing) procedure in order to estimate threshold. The computer-automated procedures were used to obtain objective estimates of evoked response thresholds in normal and hearing-impaired chinchillas. The evoked response waveforms stored in the computer were also used to obtain visual judgments of threshold. The objective thresholds determined by the computer were virtually identical to the visual detection thresholds. Thus, the computer-automated procedure provides a reliable, objective, and efficient method of estimating evoked response thresholds.