Question of asymmetries in auditory evoked potentials to speech stimuli

Abstract

It has been claimed that the auditory evoked potentials (EPs) to CV syllables differ by task (phoneme vs pitch discrimination) at left, but not right, hemisphere electrode sites [C.C. Wood, W.R. Goff, and R.S. Day, Science 173, 1248–1251 (1971); C.C. Wood, J. Exp. Psychol. 104, 3–20 (1975)]. In the present experiment, ten subjects heard synthetic CV syllables identical to those used in the Wood, Goff, and Day (1971) study. The tasks were also identical. Subjects performed a speeded choice reaction time task discriminating between the syllables /ba/ and /da/ or /ba/ (low pitch) and /ba/ (high pitch). EEG recordings (DC-48 Hz) were made from the international 10–20 system electrode sites C3 and C4 during these tasks, and EPs were averated only to the /ba/ (low-pitch) stimuli in either condition. Preliminary analysis of the results from eight of the subjects shows no significant differences between tasks at either electrode site. These preliminary results are not in agreement with the published findings cited above. [Work supported by the NIH.]