I have heard of the ‘Binaural Interaction Component’. What is this and how can it be measured using the Eclipse?
Answer: The binaural interaction component (BIC) an evoked response used to probe the binaural auditory system. Measuring it consists of a three-step process. One would need to stimulate monaurally to the left and right ears, and binaurally. The difference in response between the summed monaural responses, and the binaural response, is the BIC, and is expressed via the following equation.
The binaural response is of smaller amplitude than the sum of the two monaural responses, and this occurs at latencies of less than 10ms, while extending to tens of milliseconds. This indicates that binaural interaction involves inhibitory processes occurring as early in the auditory pathway as the brainstem and extending through to cortical regions. For a detailed review, please refer to McPherson and Starr (1993).
The Interacoustics Eclipse is able to stimulate monaurally (left and right) as well as binaurally and these options are available for ABR, AMLR and long latency evoked responses amongst others.
To find the BIC, the three waveforms would be exported1 in order to obtain the sum of left and right traces, and the differential between this sum and the binaural trace.
References and caveats
1 Exporting waveforms requires the Research Module, which also allows logging of sweeps and importing custom sound stimuli.
McPherson, D.L., and Starr, A. (1993) Binaural interaction in auditory evoked potentials: brainstem, middle- and long latency components. Hearing Research, 66 (1), pages 91-98