A method of processing ECG signals from a plurality of electrocardiogram (“ECG”) leads connected to a patient, applying the ECG signals from the ECG leads to a low-pass filter to obtain a low-band filter (“LBF”) energy values for the lead and to a high-pass filter (“HBF”) to obtain high-band filter energy values for the leads. Running averages of LBF and HBF energy values are utilized to calculate signal-to-noise (“S/N”) ratios for the leads. The S/N ratios are used to select two leads for providing ECG signals to an ECG signal processing algorithm.