Speech comprehension assessed by electroencephalography: A new method using m-sequence modulation

Electroencephalograms (EEGs) were recorded from eight Japanese speakers while they listened to Japanese and Spanish sentences (approximately 51 s each). The sentences were modulated in amplitude by a binary m-sequence and played forward or backward. A circular cross-correlation function was computed between the EEG signals and the m-sequence and averaged across subjects. Independent component analysis of the averaged function revealed a component source response which was obtained only for the comprehensible Japanese and not for the incomprehensible sentences. The present study has thus shown that a 1-min long EEG signal is sufficient for the assessment of speech comprehension.