Comparison of ABR response amplitude, test time, and estimation of hearing threshold using frequency specific chirp and tone pip stimuli in newborns.

OBJECTIVE

To evaluate the auditory brainstem response (ABR) amplitudes evoked by tone pip and narrowband chirp (NB CE-Chirp) stimuli when testing post-screening newborns and to determine the difference in estimated hearing level correction values.

DESIGN

Tests were performed with tone pips and NB CE-Chirps at 4 kHz or 1 kHz. The response amplitude, response quality (Fmp), and residual noise were compared for both stimuli.

STUDY SAMPLE

Thirty babies (42 ears) who passed our ABR discharge criterion at 4 kHz following referral from their newborn hearing screen.

RESULTS

Overall, NB CE-Chirp responses were 64% larger than the tone pip responses, closer to those evoked by clicks. Fmp was significantly higher for NB CE-Chirps.

CONCLUSION

It is anticipated that there could be significant reductions in test time for the same signal to noise ratio by using NB CE-Chirps when testing newborns. This effect may vary in practice and is likely to be most beneficial for babies with low amplitude ABR responses. We propose that the ABR nHL threshold to eHL correction for NB CE-Chirps should be approximately 5 dB less than the corrections for tone pips at 4 and 1 kHz.