Computer-aided hearing threshold determination from cortical auditory evoked potentials

The determination of the hearing threshold from cortical electric responses is usually based on the visual inspection of the recordings by an experienced evaluator. At least two factors are responsible for the limited reliability of such a procedure: first, visual inspection yields the response threshold and not the hearing threshold; and second, the result of a visual evaluation depends on subjective appraisal, which may be influenced by irrational factors. An approach of computer-aided evaluation is presented which simulates the visual inspection in that several typical features of the curves are judged numerically. The result of the classification is a single parameter, Q, whose value increases with better (subjective) perceptibility of the evoked potentials. A statistical analysis explores the relationship between the value of Q and the psychophysical hearing threshold. The results show that a prediction of hearing threshold with an accuracy of +/- 10 dB is possible.