I carried out EEG and EP studies on a daily basis. I occasionally electric artefact present within my studies, despite having my notch filter applied, low impedance, and subjects well grounded.

I figure that due is due to environment (e.g. using metal chair), as it only certain electrodes and the interference is mitigated when I adjust the wires.

My question why is the electric artefact present, despite the use of filters an earth?

Any insight and references would be great.

  • 1
    $\begingroup$ Do you mean specifically a 60 or 50 Hz oscillation from electrical supply? $\endgroup$
    – Bryan Krause
    Commented May 21, 2023 at 23:06
  • 2
    $\begingroup$ Welcome. Sample data including proper time and voltage axes can help a lot $\endgroup$
    – AliceD
    Commented May 22, 2023 at 11:26

1 Answer 1


There are many many reasons why interference can occur so it's almost impossible to give a direct answer with the details provided. You should at least give details like a spectrogram and experimental set-up. In my experiments, most (if not all) issues come down to (1) grounding and (2) line noise. For (1), you want to recheck the connections on all your grounds and ground as many sources of noise as possible. For (2), you'll want to unplug devices near your experiment one-by-one; definitely "unplug" and not "turn off" as many devices will still produce line noise even when ostensibly unpowered.


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