Stecker, MM., Bush, WW., (2001). Interference from cellular phones and the EEG. American Journal of Electroneurodiagnostic Technology, 41 (2) : 156-163.
Abstract:
Despite the high frequencies used in cellular communications, cell phones can cause significant interference in the clinical EEG when they are used within six feet of the electroencephalograph and especially when they are within one foot of the amplifier. The artifact probably appears when the signal is of such high intensity that it is processed nonlinearly by the electroencephalograph. Nonlinearities lead to the appearance of low-frequency components in the output that can appear on the EEG. This is very dependent on the amplitude of the signal. Although a previous study suggested that cellular artifact was present both near the electrodes and near the input box, we found uniformly that artifact was maximal when the cellular phone was next to the amplifiers/amplifier inputs rather than the electrodes. One reason for this is that the cable capacitance causes attenuation of very high-frequency signals in the long electrode cables often used in EEG recordings. Another reason for higher-amplitude noise levels when the cell phone was closer to the amplifiers is that high frequency signals may enter the electroencephalograph through pathways other than the electrode wires themselves.