Fig. 5.

(a) Averaged auditory-evoked field measured using the 275-channel sensor array. Among the 275 sensor recordings, the recordings from 132 sensors covering the subject's left hemisphere are displayed. Two vertical broken lines indicate the time instants 44 and 90 ms. (b) The source reconstruction results obtained using the conventional eigenspace beamformer. (c) Those from the proposed prewhitening beamformer. The left, middle, and right columns show the maximum intensity projections of the 3-D reconstruction onto the axial, coronal, and sagittal planes, respectively. The upper case letters L and R show the left and the right hemispheres, respectively. The upper and lower panels indicate the reconstruction results at 44 and 90 ms, respectively. In these reconstruction results, the reconstruction grid has 0.5-cm intervals in the x, y, and z directions.