Attenuation in the frequency bins provoked by application of (a) OMA and (b) AAS for an EEG excerpt picked up from the channel CPz (Philips data), taking into account different values of and number of averaging epochs. Although OMA and AAS can provide similar EEG preservation (same value of SNR and MSE), OMA is more effective in attenuating the artefact in the overall frequency bins, mainly in higher-frequencies than 100 Hz.