Simultaneous Recording of Multiple Auditory Brainstem Responses at Clinical Discharge Level.

OBJECTIVES: This study investigated changes in auditory brainstem response (ABR) wave-V morphology when multiple ABRs were recorded simultaneously using MultiBand ABR, compared with the traditional method of consecutive stimulus presentation. DESIGN: ABRs were elicited using narrow-band (NB) CE-Chirps centered at 500, 1000, 2000, and 4000 Hz, presented at clinical discharge levels and 10 dB above these levels. Both simultaneous and consecutive presentation modes were conducted at a nominal rate of 40 stimuli per second for each NB CE-Chirp. A total of 24 young participants with normal hearing were included, resulting in data from 48 ears at the discharge level and 20 participants (40 ears) at discharge level +10 dB. RESULTS: In the consecutive presentation mode, ABR wave-V morphology exhibited typical mean latency and amplitude characteristics for each NB CE-Chirp at both discharge level and discharge level +10 dB. However, in the simultaneous recording condition, ABRs demonstrated significantly longer wave-V latencies for the 500 and 1000 Hz stimuli at discharge level, and for the 500, 1000, and 2000 Hz stimuli at discharge level +10 dB, compared with the consecutive presentation. Furthermore, at both discharge and discharge level +10 dB, wave-V amplitudes were significantly reduced for all NB CE-Chirp stimulus frequencies in the simultaneous mode compared with the consecutive mode. Within-session test-retest evaluations were performed for the simultaneous presentation at discharge level, revealing no significant differences in wave-V amplitude or latency between the two recordings. CONCLUSIONS: These findings support the hypothesis of a partial masking effect on the compound neural response to the target NB CE-Chirp caused by the presence of the adjacent off-frequency stimuli, suggesting a potential increase in ABR place specificity when using the simultaneous presentation method.