[Electrophysiologic studies of hearing: current methods in clinical and occupational audiology. I. Brain stem evoked response audiometry (ABR)].

Electrophysiological methods of auditory assessment called evoked responses are an exciting new development with broad implications in the fields of otology, audiology and neurology. At the present time they are the best objective non-invasive audiometric tests (versus subjective psychoacoustic examinations) for predicting hearing thresholds in infants and uncooperative patients. Basic concepts of electric response audiometry, most important auditory evoked potentials, their probable sites of generation and classification according to latency i.e. elapsed time between stimulus and response are reviewed. Instrumentation, procedure and technical considerations in recording the brain-stem evoked response audiometry (ABR), the most popular recent method for evoked potentials testing are described. Special attention is focused on measurement, identification and interpretation of brainstem responses and their major clinical uses, namely threshold testing of infants, young children and malingerers, diagnosis of acoustic tumors and neurological evaluation of brainstem lesions. Finally, the first own experience with a new employed in our laboratory the evoked potentials system Amplaid MK 10 for clinical testing of auditory pathways are presented and illustrated by some examples of application of brainstem audiometry in diagnosis of occupational noise-induced hearing loss.