Measures of the binaural interaction component in human auditory brainstem response using objective detection criteria

The occurrence of binaural interaction in humans has been demonstrated using auditory brainstem response (ABR). A distinctly binaural potential, beta, is derived by subtracting the ABR recording evoked by binaural clicks from the monaural aggregate, i.e., the sum of the two corresponding ABR recordings evoked by monaural clicks. However, few clinical data are available, possibly because the beta-wave is considered an elusive response due to a low signal-to-noise-ratio. In the present study, beta-wave latency, amplitude and area were evaluated for 10 subjects with normal hearing using automatic analysis and averaging based on a large number of stimulations. The efficacy of the beta-wave measures was assessed using different stimulus rates, as binaural interaction is known to decrease with increasing stimulus rate. It was found that the beta-wave given by automatic analysis demonstrated known characteristics of binaural interaction in human ABR, i.e. the absence of binaural interaction during wave In, significant binaural interaction during wave V and a significant decrease in binaural interaction when the stimulus rate was increased. These findings suggest that a beta-wave in the binaural difference waveform can be detected and quantified using automatic analysis, thus it is suitable for clinical studies, at least for patients with normal hearing thresholds.