Using ASSR with narrow-band chirps to evaluate hearing in children and adults.

Purpose: All studies concerning the reliability and threshold prediction of auditory steady-state responses (ASSR) focused on a particular group of patients. The present article evaluates the use of narrow-band, chirp-evoked ASSR for testing hearing in adults and children of all ages and with different types of hearing loss, as well as normal hearing. The aims are: to determine whether there are possible influencing factors, mainly the degree of hearing loss; and to validate the clinical value of using ASSR with chirp-stimuli.

Methods: This is a retrospective study of 667 patients who had been diagnosed with and treated for hearing loss at our tertiary referral center. The following results were compared: ASSR to pure tone audiometry (PTA); click-ABRs to PTA; and click-ABRs to ASSR. We then calculated mean, median and standard deviation. A regression analysis was used to examine the correlation between: ASSR and click-ABRs; "estimated" audiogram and PTA; click-ABRs and PTA; and ASSR and PTA.

Results: We found significant correlations at all frequencies when comparing ASSR to click-ABRs, click-ABRs to PTA, and ASSR to PTA. Concerning the degree of hearing loss, there were significant differences between the patients with normal hearing and those with moderate-to-profound hearing loss.

Conclusion: ASSR with narrow-band chirps are a reliable tool for estimating hearing thresholds in children and adults with all kinds of hearing loss. We have demonstrated that threshold differences between PTA and ASSR are negligible in the clinical routine. The "estimated" ASSR audiogram is a good approach for communicating ASSR results to the average user.