Evoked cerebral potential audiometry and hearing threshold.

Audiometric testing by means of the nonspecific evoked cerebral potential (NECP) was performed in 20 children (11 with normal hearing, 6 with conductive and 3 with sensorineural hearing loss). The threshold as determined by this method was 20-30 dB higher than the threshold of the subjective tonal audiograms in the majority of the cases. Only in two cases the difference was up to 70 dB. There were no significant differences between the results of the methods in the three groups of children. The possible reasons for the described discrepancy between the thresholds of the ECP audiometry and the subjective tonal audiometry are discussed. It is pointed out that either of the two methods explores one of two different functional systems: the nonspecific activating system of the brain stem and the auditory pathway. It is suggested that the observed discrepancy between the results of the two methods may mainly be due to different thresholds of the two systems. To avoid false negative results of the ECP audiometry in subjects with 'constitutionally' low amplitude of the NECP it is proposed to routinely determine the amplitude of the NECP produced by somatosensory stimuli. Careful evaluation of the recorded data can improve the diagnostic value of ECP audiometry.