Impedances The higher the impedance–the resistance to passage of the signal between the scalp and the electrode metal–the poorer your signal will be and the more likely you are to have electromagnetic fields enter artifact into the signal. High impedances are usually the result of poor connections. If you have high impedances, redo your connections. 60 Hz is always and everywhere present in any US environment. Think of the old analog radios that you had to tune in by turning […]