Figure 3.

Differences of ${\sigma }_{\left|\widehat{N}\left(f\right)\right|}$ (a) ${\mathrm{ECG}}_{\mathrm{raw}}$ vs ${\mathrm{ECG}}_{\mathrm{PLn}}$ (b) ${\mathrm{ECG}}_{\mathrm{raw}}$ vs ${\mathrm{ECG}}_{\mathrm{EMG}}$.