EEG correlates of speech: Examination of event related potentials elicited by phoneme classes

This paper reports on a preliminary study carried out to examine whether the phoneme classes defined by linguists elicit distinguishable electroencephalographic (EEG) responses from the brain. To this end event-related potentials (ERP) were recorded in response to three-syllabic nonsense words (non-words) with three consonant-vowel transitions (CVCVCV). The first syllable of the non-words being fixed, ERPs were triggered from the onset of the middle syllable, which was established by manually segmenting the non-words at phoneme level. The ERP responses elicited by the second syllable were examined. Nonparametric t-tests were carried out to compare the different ERP responses of the middle syllable. The results show that different ERPs were produced by consonants belonging to different phonemic categories (fricatives, plosives, liquids, nasals and affricates). ERP amplitudes and their scalp distribution differed from each other across non-similar phonetic categories. Consonants from the same phonemic category elicited similar ERP responses. Further, the scalp distributions of the ERP responses were characteristically different for different phoneme classes of consonants. These results suggest that the manner of articulation is an important component of the phonetic representation of consonants in the brain.