Last Updated on July 30, 2022 by pg@petergamma.org It only measures the voltage between 2 electrodes, the 3. electrode being ground. Technically, Dr. Scott Hardens PhD. Sound Card ECG is a: (3 electrode) 1 lead ECG system According to the scientific papers, reference devices for sports sensor accuracy validation have up to 3 channels (or … Continue reading Dr. Scott Hardens (MD., PhD.) Sound Card ECG is only a (3 electrode) 1 lead ECG system