Averaging signal's energy density in the time-frequency plane

Time-frequency distribution (map) of signal's energy density contains no information about the phase of signal's structures. We estimate this magnitude--by means of the the MP procedure described in the previous sections--separately for all the single trials, and then average resulting maps. Such an average (Figures 4-6) enhances structures bearing similar time-frequency signatures--i.e. occurring in the same time-frequency region, as related to the trigger--irrelevant of their phase relations. Contrary to the averaging in the time domain, it allows to pick from noise also those phenomena, where phase synchronization does not occur, or, as in high frequencies, can be distorted by limited accuracy of the trigger's time localization. This approach was briefly presented at a conference [2].