Comparing laboratory and portable tone-burst auditory brain-stem-response (ABR) systems for monitoring high-frequency...

High-frequency (8-20 kHz) hearing sensitivity is of special interest because of its early warning potential for ototoxicity. Many ill patients, however, are unable to respond behaviorally to auditory test procedures. To objectively monitor high-frequency auditory function in these patients, laboratory instrumentation to evoke the auditory brain-stem response (ABR) with high-frequency (8-14 kHz) tone-burst stimuli was developed and documented. To provide evaluation at bedside, a portable high-frequency tone-burst generator was developed to elicit the ABR. Combined with a portable signal averager, this system was validated by comparison with the laboratory system. Thirty-five normal-hearing subjects were used to compare ABRs to high-frequency tone bursts from each system. Analysis of responses to tone bursts revealed no significant mean latency differences, and no significant intersession reliability differences between systems. These results confirm that the portable system is comparable to the laboratory system in obtaining reliable high-frequency tone-burst responses.