Steady state auditory evoked potentials in normal hearing subjects: evaluation of threshold and testing time.

Background: Steady state responses (SSRs), between 75 and 110 Hz, evoked by auditory amplitude modulated single or multiple tone stimuli, may be used to estimate objective hearing threshold.

Methods: The aim of this study was to compare SSRs and click-evoked auditory brainstem responses (ABRs) in both ears of 20 adults (10 males and 10 females, aged between 24 and 36 years) with normal hearing threshold.

Results: Mean ABR threshold was found at 21.25 (± 5.9) dB nHL. Mean SSR threshold was found at 15.6 (± 9.6) dB nHL after a single frequency stimulus (1 kHz); at 10.5 (± 18.2) dB nHL and at 7.1 (± 12.4) dB nHL after bifrequency stimulation (0.5 and 2 kHz). SSR thresholds after multifrequency stimulation (0.5, 1, 2 and 4 kHz) were found, respectively, at 12.1 (± 12.9) dB nHL, 12.2 (± 12.8) dB nHL, 12.3 (± 8.3) dB nHL and 18.9 (± 17.2) dB nHL. Mean duration of the recording session was 6 min in the case of ABRs, while it was 25 min in the single frequency condition and 29 min in the multifrequency condition in the case of SSRs.

Conclusion: SSRs can be used for frequency-specific objective audiometry. The multifrequency stimulation greatly reduces the whole testing time.