[Steady-state responses of the auditory system: a comparison of different methods].

BACKGROUND: Determining the hearing threshold in children is one of the most important topics in audiology. Because the existing methods-brainstem evoked response audiometry (BERA) and cortical evoked response audiometry (CERA)-show some severe insufficiencies, it is necessary to look for improved methods. A promising approach may be amplitude modulation following responses (AMFR). In contrast to the conventional transient auditory evoked potentials, these responses show a high-frequency specificity, and they possibly allow statements about the hearing threshold in the low-frequency range. SUBJECTS AND METHODS: The purpose of our study was to objectively detect the hearing threshold in normal-hearing persons of various ages. Pure-tone audiometry served as a subjective control test. For objective tests, we used the measurement of AMFR (two different systems with distinct parameters) and CERA. We compared the different methods with regard to accuracy of the determination of the hearing threshold and investigated the practicability.
RESULTS: The results showed some large deviations between the subjective hearing threshold and the objectively determined responses. The lowest deviations appeared at low frequencies. With respect to the variability of results, CERA was clearly superior to AMFR.
CONCLUSION: Despite large deviations in the responses objectively determined by AMFR, we think AMFR is suitable to close some gaps in determining objective hearing thresholds, at least at low frequencies.