[Significance of ERA for differentiating hearing disorders of different origins]

The reliability on audiometric findings in hearing disorders of different genesis has been considerably improved by the ERA. By no means, the ERA can replace the conventional hearing tests, rather it is an additional technique of examination. Apparently it does not reveal specific findings of psychogenic hearing disorders - unless the prolongation of the cortical response as repeatedly seen by us. In case of aggravation ERA renders us possible to detect the kind of hearing defects and the actual threshold - e.g. with respect to high frequency range by brain stem responses, for 500 and 1,000 Hz according to the cortical responses. The neural hearing impairment caused by tumours always exhibits extremely prolonged latencies even at high intensities, eventually concomitant with a response threshold elevated versus the subjective threshold. These reactions, above all, become apparent in the brain stem rather than in the cortex. In contrast to this the sensoric hearing disorders the ERA elucidates even objectively the recruitment: normal latencies at high intensities. The latency of the objective response, thus, corresponds to the sound stimulus is perceived loud, and it is long for stimuli perceived relatively low - even in spite of great intensity. Comprising the ERA the quote of audiometric failures in excluding an acoustic neuroma is reduced to a minimum.