Methodological problems in the investigation of cerebral potentials preceding speech: Determining the onset and suppressing artefacts caused by speech

Abstract Artefact influences on brain potentials preceding speech and phonation are investigated in 42 separate experiments with 17 subjects. The method of time-reversed averaging of tape stored data was used for analysis [13]. The following possible artefact contaminations were proved and/or discussed: GSR, electrical field artefacts, head and lead movements, EMG influences, eye blinks, glossokinetic potentials, positions of reference electrodes and time constants. The elimination of the discussed artefacts supports the intracranial origin of the recorded potentials. Previously reported interhemispheric asymmetries of brain potentials preceding speech and similar activities [4, 6–10] therefore represent a biolectric correlate of hemispheric dominance.