Evaluation of diagnostic audiometric tests.

Abstract

Five diagnostic audiometric procedures - acoustic reflexes, performance-intensity functions for monosyllabic (phonetically balanced) words, Békésy audiometry, Békésy comfortable loudness audiometry and suprathreshold adaptation test - were critically evaluated by decision matrix analysis and information theory analysis. The subjects were 20 patients with surgically confirmed eighth nerve disorders and 20 patients with presumed cochlear disorders. Each patient completed all test procedures. In terms of decision matrix analysis, sensitivity (correct identification of eighth nerve site) ranged from 45 to 85%. Specificity (correct rejection of patients with cochlear site) ranged from 70 to 100%. Predictive value ranged from 74 to 100% for positive results and from 62 to 82% for negative results. The efficiency of the five tests ranged from 68 to 78%. In terms of information theory, positive test results increased the probability of eighth nerve disorder in any subject from 50% (a priori) to 74-100%. Negative test results decreased the probability of eighth nerve disorder from 50% to 18-38%. Relative differences among the diagnostic effectiveness of the five individual test procedures were not pronounced. However, the suprathreshold adaptation test (results confined to 500, 1 000 and 2 000 Hz) was less efficient than the other four diagnostic techniques.