Rate, frequency, and intensity effects on early auditory evoked potentials and binaural interaction component in humans.

The binaural interaction component (BIC) of the auditory brainstem response (ABR) and BIC of the frequency-following response (FFR) to tonal stimuli were studied in normal-hearing adults. The ABR and BIC latencies from all subjects were consistently shorter to the click-like sound than to the 2.0 kHz tone burst. Increasing stimulus presentation rate produced longer latencies and diminished amplitudes of ABR and BIC waveforms. The consequences of rate changes were independent of sound level. The FFR and BIC latencies to low-frequency tone bursts (0.5 and 1.0 kHz) were minimally affected by rate, but their amplitudes were modified. The results are consistent with and reflective of the functional characteristics of lower brainstem auditory neurons. The results provide evidence that the BIC to tones is differentially sensitive to the rate, frequency, and intensity of sounds other than clicks.