Auditory Brainstem Response Binaural Interaction Components Measured With Low-Frequency Tone Bursts: Correlations...

This study aimed to identify electrophysiological markers of binaural processing at the brainstem level and examine whether they may serve as electrophysiological correlates of behavioral performance in young adults with normal hearing.

Twenty-nine young adults (21-29 years) with symmetric normal hearing (≤ 20 dB HL) were tested. Binaural processing was measured using the binaural interaction component (BIC) of the auditory brainstem response (ABR) elicited by 250- and 500-Hz tone bursts. Behavioral performance was assessed with three tasks: spondee binaural fusion (SBF), 500-Hz masking level difference, and auditory figure-ground.

For ABR-BIC latency, VI_d occurred later than V_d, and both waves showed longer latencies at 250 Hz than at 500 Hz. The later timing of VI_d could be associated with later processing along more rostral auditory pathways. At 500 Hz, V_d amplitude was significantly larger than VI_d, whereas amplitudes were comparable at 250 Hz, suggesting that VI_d may be relatively preserved at lower frequencies. ABR-BIC VI_d amplitude at 250 Hz correlated significantly with SBF scores, with larger VI_d amplitudes associated with higher scores.

ABR-BIC Waves V_d and VI_d may reflect different electrophysiological aspects of brainstem-level binaural processing. VI_d amplitude at 250 Hz may serve as a preliminary electrophysiological correlate of binaural fusion performance, although this single association should be interpreted cautiously and replicated in future studies. ABR-BIC may have potential as an objective supplement to behavioral binaural measures, although further validation is needed.