A region on the head is examined with respect to the different muscles present in the region, and correlation areas are defined, where not two correlation areas relate to the same muscle in the region. The EEG probes are then produced individually for the examined human in order to optimize positioning of the electrodes on the different correlation areas. This way, signals from the muscles can be filtered out relatively easy when combining the signals from the different electrodes because the signals are not correlated between the electrodes, in contrast to the EEG signals.
