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.