Fig. 4From: Noise-assisted multivariate empirical mode decomposition for multichannel EMG signalsSpectra of normalized IMFs (IMF1-IMF4 for EEMD, IMF1-IMF5 for MEMD, and IMF1-IMF6 for NA-MEMD) obtained from four-channel EMG signals (RF, BF, VM, and ST) via EEMD (a), MEMD (b) and NA-MEMD (c). Overlapping of the frequency bands corresponding to the same-index IMFs is more prominent in the cases of MEMD and NA-MEMD but the NA-MEMD bands clearly show much better alignmentBack to article page