Orderly organization of vowels in the auditory brain

The neuronal correlates of the Italian vowels

Abstract

The main novelty of the study consists in using the EEG technique to elucidate the functioning of the auditory cortex in speech sound information processing. In searching for the cortical responses of two Italian vowels [a] and [i] we demonstrate that (i) as for the magnetic fields, also the modulations of the early electric N1 component is useful in exploring the mechanisms of phonetic feature extraction. The N1 amplitude and the N1 cortical generators seem to be affected by the vowel features as mapped in F2/F1 ratio so that the vowel [a] that shows a reduced inter-formant distance evokes weaker and anterior activity than [i]. The study thus, confirms that the cortical activity reflects the main spectro-acoustic dissimilarities supporting tonotopy as one of the most prominent organizing rules of the auditory cortices.